title: RAID

paragraphs: RAID is an acronym that stands for Redundant Array of Inexpensive Disks or Redundant Array of Independent Disks. RAID is a term used in computing. With RAID, several hard disks are made into one logical disk. There are different ways this can be done. Each of the methods that puts the hard disks together has some benefits and drawbacks over using the drives as single disks, independent of each other. The main reasons why RAID is used are:

paragraphs: It is not possible to achieve all of these goals at the same time, so choices need to be made.

paragraphs: Most of the work on RAID is based on a paper written in 1988.

paragraphs: Companies have used RAID systems to store their data since the technology was made. There are different ways in which RAID systems can be made. Since its discovery, the cost of building a RAID system has come down a lot. For this reason, even some computers and appliances that are used at home have some RAID functions. Such systems can be used to store music or movies, for example.

paragraphs: A hard disk is a part of a computer. Normal hard disks use magnetism to store information. When hard disks are used, they are available to the operating system. In Microsoft Windows, each hard disk will get a drive letter (starting with C:, A: or B: are reserved for floppy drives). Unix and Linux-like operating systems have a single-rooted directory tree. This means that people who use the computers sometimes do not know where the information is stored.(To be fair, a lot of Windows users don't know where their data is stored as well.)

paragraphs: In computing, the hard disks (which are hardware, and can be touched) are sometimes called "physical drives" or "physical disks". What the operating system shows the user is sometimes called "logical disk". A physical drive can be split into different sections, called disk partitions. Usually, each disk partition contains one file system. The operating system will show each partition like a logical disk.

paragraphs: Therefore, to the user, both the setup with many physical disks and the setup with many logical disks will look the same. The user cannot decide if a "logical disk" is the same as a physical disk, or if it simply is a part of the disk. Storage Area Networks (SANs) completely change this view. All that is visible of a SAN is a number of logical disks.

paragraphs: In the computer, data is organised in the form of bits and bytes. In most systems, 8 bits make up a byte. Computer memory uses electricity to store the data, hard disks use magnetism. Therefore, when data is "written" on a disk, the electric signal is converted into a magnetic one. When data is read from disk, the conversion is done in the other direction: An electrical signal is made from the polarity of a magnetic field.

paragraphs: A RAID array joins two or more hard disks so that they make a logical disk. There are different reasons why this is done. The most common ones are:

paragraphs: RAID is done by using special hardware or software on the computer. The joined hard disks will then look like one hard disk to the user. Most RAID levels increase the redundancy. This means that they store the data more often, or they store information on how to reconstruct the data. This allows for a number of disks to fail without the data being lost. When the failed disk is replaced, the data it should contain will be copied or rebuilt from the other disks of the system. This can take a long time. The time it takes depends on different factors, like the size of the array.

paragraphs: One of the reasons why many companies are using RAID is that the data in the array can simply be used. Those using the data need not be aware they are using RAID at all. When a failure occurred and the array is recovering, access to the data will be slower. Accessing the data during this time will also slow down the recovery process, but this is still much faster than not being able to work with the data at all.

paragraphs: Depending on the RAID level however, disks may not fail while the new disk is being prepared for use. A disk failing at that time will result in losing all the data in the array.

paragraphs: The different ways to join disks are called "RAID levels". A bigger number for the level is not necessarily better. Different RAID levels have different purposes. Some RAID levels need special disks and special controllers.

paragraphs: In 1978, a man called Norman Ken Ouchi, who worked at IBM, made a suggestion describing the plans for what would later become RAID 5. The plans also described something similar to RAID 1, as well as the protection of a part of RAID 4.

paragraphs: Workers at the University of Berkeley helped to plan out research in 1987. They were trying to make it possible for RAID technology to recognize two hard drives instead of one. They found that when RAID technology had two hard drives, it had much better storage than with only one hard drive. However, it crashed much more often.

paragraphs: In 1988, the different types of RAID (1 to 5), were written about by David Patterson, Garth Gibson and Randy Katz in their article, called "A Case for Redundant Arrays of Inexpensive Disks (RAID)". This article was the first to call the new technology RAID and the name became official.

paragraphs: RAID uses a few basic ideas, which were described in the article "RAID: High-Performance, Reliable Secondary Storage" by Peter Chen and others, published in 1994.

paragraphs: Caching is a technology that also has its uses in RAID systems. There are different kinds of caches that are used in RAID systems:

paragraphs: In modern systems, a write request is shown as done when the data has been written to the cache. This does not mean that the data has been written to the disk. Requests from the cache are not necessarily handled in the same order that they were written to the cache. This makes it possible that, if the system fails, sometimes some data has not been written to the disk involved. For this reason, many systems have a cache that is backed by a battery.

paragraphs: When talking about a mirror, this is a very simple idea. Instead of the data being in only one place, there are several copies of the data. These copies usually are on different hard disks (or disk partitions). If there are two copies, one of them can fail without the data being affected (as it still is on the other copy). Mirroring can also give a boost when reading data. It will always be taken from the fastest disk that responds. Writing data is slower though, because all disks need to be updated.

paragraphs: With striping, the data is split into different parts. These parts then end up on different disks (or disk partitions). This means that writing data is faster, as it can be done in parallel. This does not mean that there will not be faults, as each block of data is only found on one disk.

paragraphs: It is possible to calculate different kinds of checksums. Some methods of calculating checksums allow finding a mistake. Most RAID levels that use redundancy can do this. Some methods are more difficult to do, but they allow to not only detect the error, but to fix it.

paragraphs: Many of the ways to have RAID support something is called a "hot spare". A hot spare is an empty disk that is not used in normal operation. When a disk fails, data can directly be copied onto the hot spare disk. That way, the failed disk needs to be replaced by a new empty drive to become the hot spare.

paragraphs: RAID works by spreading the data over several disks. Two of the terms often used in this context are "stripe size" and "chunk size".

paragraphs: The "chunk size" is the smallest data block that is written to a single disk of the array. The "stripe size" is the size of a block of data that will be spread over all disks. That way, with four disks, and a stripe size of 64 kilobytes (kB), 16 kB will be written to each disk. The chunk size in this example is therefore 16 kB. Making the stripe size bigger will mean a faster data transfer rate, but also a bigger maximum latency. In this case, this is the time needed to get a block of data.

paragraphs: Many controllers (and also software) can put disks together in the following way: Take the first disk, till it ends, then they take the second, and so on. In that way, several smaller disks look like a larger one. This is not really RAID, as there is no redundancy. Also, spanning can combine disks where RAID 0 cannot do anything. Generally, this is called "just a bunch of disks" (JBOD).

paragraphs: This is like a distant relative of RAID because the logical drive is made of different physical drives. Concatenation is sometimes used to turn several small drives into one larger useful drive. This can not be done with RAID 0. For example, JBOD could combine 3 GB, 15 GB, 5.5 GB, and 12 GB drives into a logical drive at 35.5 GB, which is often more useful than the drives alone.

paragraphs: In the diagram to the right, data are concatenated from the end of disk 0 (block A63) to the beginning of disk 1 (block A64); end of disk 1 (block A91) to the beginning of disk 2 (block A92).

paragraphs: If RAID 0 were used, then disk 0 and disk 2 would be truncated to 28 blocks, the size of the smallest disk in the array (disk 1) for a total size of 84 blocks.

paragraphs: Some RAID controllers use JBOD to talk about working on drives without RAID features. Each drive shows up separately in the operating system. This JBOD is not the same as concatenation.

paragraphs: Many Linux systems use the terms "linear mode" or "append mode". The Mac OS X 10.4 implementation — called a "Concatenated Disk Set" — does not leave the user with any usable data on the remaining drives if one drive fails in a concatenated disk set, although the disks otherwise operate as described above.

paragraphs: Concatenation is one of the uses of the Logical Volume Manager in Linux. It can be used to create virtual drives.

paragraphs: Most modern hard disks have a standard called Self-Monitoring, Analysis and Reporting Technology (S.M.A.R.T). SMART allows to monitor certain things on a hard disk drive. Certain controllers allow to replace a single hard disk even before it fails, for example because S.M.A.R.T or another disk test reports too many correctable errors. To do this, the controller will copy all the data onto a hot spare drive. After this, the disk can be replaced by another (which will simply become the new hot spare).

paragraphs: The setup of the disks and how they use the techniques above affects the performance and reliability of the system. When more disks are used, one of the disks is more likely to fail. Because of this, mechanisms have to be built to be able to find and fix errors. This makes the whole system more reliable, as it is able to survive and repair the failure.

paragraphs: RAID 0 is not really RAID because it is not redundant. With RAID 0, disks are simply put together to make a large disk. This is called "striping". When one disk fails, the whole array fails. Therefore, RAID 0 is rarely used for important data, but reading and writing data from the disk can be faster with striping because each disk reads part of the file at the same time.

paragraphs: With RAID 0, disk blocks that come after one another are usually placed on different disks. For this reason, all disks used by a RAID 0 should be the same size.

paragraphs: RAID 0 is often used for Swapspace on Linux or Unix-like operating systems.

paragraphs: With RAID 1, two disks are put together. Both hold the same data, one is "mirroring" the other. This is easy, fast configuration whether implemented with a hardware controller or by software.

paragraphs: RAID Level 5 is what is probably used most of the time. At least three hard disks are needed to build a RAID 5 storage array. Each block of data will be stored in three different places. Two of these places will store the block as it is, the third will store a checksum. This checksum is a special case of a Reed-Solomon code that only uses bitwise addition. Usually, it is calculated using the XOR method. Since this method is symmetric, one lost data block can be rebuilt from the other data block and the checksum. For each block, a different disk will hold the parity block which holds the checksum. This is done to increase redundancy. Any disk can fail. Overall, there will be one disk holding the checksums, so the total usable capacity will be that of all disks except for one. The size of the resulting logical disk will be the size of all disks together, except for one disk which holds parity information.

paragraphs: Of course this is slower than RAID level 1, since on every write, all disks need to be read to calculate and update the parity information. The read performance of RAID 5 is almost as good as RAID 0 for the same number of disks. Except for the parity blocks, the distribution of data over the drives follows the same pattern as RAID 0. The reason RAID 5 is slightly slower is that the disks must skip over the parity blocks.

paragraphs: A RAID 5 with a failed disk will continue to work. It is in "degraded mode". A degraded RAID 5 can be very slow. For this reason an additional disk is often added. This is called "hot spare" disk. If a disk fails, the data can be directly rebuilt onto the extra disk. RAID 5 can also be done in software quite easily.

paragraphs: Mainly because of performance problems of failed RAID 5 arrays, some database experts have formed a group called BAARF—the "Battle Against Any Raid Five".

paragraphs: If the system fails while there are active writes, the parity of a stripe may become inconsistent with the data. If this is not repaired before a disk or block fails, data loss may occur. An incorrect parity will be used to reconstruct the missing block in that stripe. This problem is sometimes known as the "write hole". Battery-backed caches and similar techniques are commonly used to reduce the chance for this to occur.

paragraphs: This was used with very large computers. Special expensive disks and a special controller are needed to use RAID Level 2. The data is distributed at the bit-level (all other levels use byte-level actions). Special calculations are done. Data is split up into static sequences of bits. 8 data bits and 2 parity bits are put together. Then a Hamming code is calculated. The fragments of the Hamming code are then distributed over the different disks.

paragraphs: RAID 2 is the only RAID level that can "repair" errors, the other RAID levels can only detect them. When they find that the information needed does not make sense, they will simply rebuild it. This is done with calculations, using information on the other disks. If that information is missing or wrong, they cannot do much. Because it uses Hamming codes, RAID 2 can find out which piece of the information is wrong, and correct only that piece.

paragraphs: RAID 2 needs at least 10 disks to work. Because of its complexity and its need for very expensive and special hardware, RAID 2 is no longer used very much.

paragraphs: Raid Level 3 is much like RAID Level 0. An additional disk is added to store parity information. This is done by bitwise addition of the value of a block on the other disks. The parity information is stored on a separate (dedicated) disk. This is not good, because if the parity disk crashes, the parity information is lost.

paragraphs: RAID Level 3 is usually done with at least 3 disks. A two-disk setup is identical to a RAID Level 0.

paragraphs: This is very similar to RAID 3, except that the parity information is calculated over larger blocks, and not single bytes. This is like RAID 5. At least three disks are needed for a RAID 4 array.

paragraphs: RAID level 6 was not an original RAID level. It adds an additional parity block to a RAID 5 array. It needs at least four disks (two disks for the capacity, two disks for redundancy). RAID 5 can be seen as a special case of a Reed-Solomon code. RAID 5 is a special case, though, it only needs addition in the Galois field "GF(2)". This is easy to do with XORs. RAID 6 extends these calculations. It is no longer a special case, and all of the calculations need to be done. With RAID 6, an extra checksum (called polynomial) is used, usually of "GF (2)". With this approach it is possible to protect against any number of failed disks. RAID 6 is for the case of using two checksums to protect against the loss of two disks.

paragraphs: Like with RAID 5, parity and data are on different disks for each block. The two parity blocks are also located on different disks.

paragraphs: There are different ways to do RAID 6. They are different in their write performance, and in how much calculations are needed. Being able to do faster writes usually means more calculations are needed.

paragraphs: RAID 6 is slower than RAID 5, but it allows the RAID to continue with any two disks failed. RAID 6 is becoming popular because it allows an array to be rebuilt after a single-drive failure even if one of the remaining disks has one or more bad sectors.

paragraphs: RAID 6 uses two parity blocks. These are calculated in a special way over a polynomial. "Double parity" RAID (also called "diagonal parity" RAID) uses a different polynomial for each of these parity blocks. Recently, the industry association that defined RAID said that double parity RAID is a different form of RAID 6.

paragraphs: RAID-DP is another way of having double parity.

paragraphs: RAID 1.5 (not to be confused with RAID 15, which is different) is a proprietary RAID implementation. Like RAID 1, it only uses two disks, but it does both striping and mirroring (similar to RAID 10). Most things are done in hardware.

paragraphs: RAID 5E, RAID 5EE and RAID 6E (with the added "E" for "Enhanced") generally refer to different types of RAID 5 or RAID 6 with a hot spare. With these implementations, the hot spare drive is not a physical drive. Rather, it exists in the form of free space on the disks. This increases performance, but it means that a hot spare cannot be shared between different arrays. The scheme was introduced by IBM ServeRAID around 2001.

paragraphs: This is a proprietary implementation. It adds caching to a RAID 3 or RAID 4 array.

paragraphs: Some Intel main boards have RAID chip that have this feature. It uses two or three disks, and then partitions them equally to form a combination of RAID 0, RAID 1, RAID 5 or RAID 1+0 levels.

paragraphs: This is the name for the driver that allows to do software RAID with Linux. In addition to the normal RAID levels 0-6, it also has a RAID 10 implementation. Since Kernel 2.6.9, RAID 10 is a single level. The implementation has some non-standard features.

paragraphs: Sun has implemented a file system called ZFS. This file system is optimised for handling large amounts of data. It includes a Logical Volume Manager. It also includes a feature called RAID-Z. It avoids the problem called "RAID 5 write hole" because it has a copy-on-write policy: It does not overwrite the data directly, but writes new data in a new location on the disk. When the write was successful, the old data is deleted. It avoids the need for read-modify-write operations for small writes, because it only writes full-stripes. Small blocks are mirrored instead of parity protected, which is possible because the file system knows the way the storage is organised. It can therefore allocate extra space if necessary. There is also "RAID-Z2" which uses two forms of parity to achieve results similar to RAID 6: the ability to survive up to two drive failures without losing data.

paragraphs: With RAID different disks can be put together to get a logical disk.The user will only see the logical disk. Each one of the RAID levels mentioned above has good and bad points. But RAID can also work with logical disks. That way one of the RAID levels above can be used with a set of logical disks. Many people note it by writing the numbers together. Sometimes, they write a '+' or an '&' in between. Common combinations (using two levels) are the following:

paragraphs: With six disks of 300 GB each, a total capacity of 1.8TB, it is possible to make a RAID 5, with 1.5 TB usable space. In that array, one disk can fail without data loss. With RAID 50, the space is reduced to 1.2 TB, but one disk of each RAID 5 can fail, plus there is a noticeable increase in performance. RAID 51 reduces the usable size to 900 GB, but allows any three drives to fail.

paragraphs: There are different ways to make a RAID. It can either be done with software, or with hardware.

paragraphs: A RAID can be made with software in two different ways. In the case of Software RAID, the disks are connected like normal hard disks. It is the computer that makes the RAID work. This means that for each access the CPU also needs to do the calculations for the RAID. The calculations for RAID 0 or RAID 1 are simple. However, the calculations for RAID 5, RAID 6, or one of the combined RAID levels can be a lot of work. In a software RAID, automatically booting from an array that failed may be a difficult thing to do. Finally, the way RAID is done in software depends on the operating system used; it is generally not possible to re-build a Software RAID array with a different operating system. Operating systems usually use hard disk partitions rather than whole hard disks to make RAID arrays.

paragraphs: A RAID can also be made with hardware. In this case, a special disk controller is used; this controller card hides the fact that it is doing RAID from the operating system and the user. The calculations of checksum information, and other RAID-related calculations are done on a special microchip in that controller. This makes the RAID independent of the operating system. The operating system will not see the RAID, it will see a single disk. Different manufacturers do RAID in different ways. This means that a RAID built with one hardware RAID controller cannot be rebuilt by another RAID controller of a different manufacturer. Hardware RAID controllers are often expensive to buy.

paragraphs: This is a mix between hardware RAID and software RAID. Hardware-assisted RAID uses a special controller chip (like hardware RAID), but this chip can not do many operations. It is only active when the system is started; as soon as the operating system is fully loaded, this configuration is like software RAID. Some motherboards have RAID functions for the disks attached; most often, these RAID functions are done as "hardware-assisted RAID". This means that special software is needed to be able to use these RAID functions and to be able to recover from a failed disk.

paragraphs: There are different terms that are used when talking about hardware failures:

paragraphs: The failure rate is how often a system fails. The "mean time to failure" (MTTF) or "mean time between failures" (MTBF) of a RAID system is the same as that of its components. A RAID system cannot protect against failures of its individual hard drives, after all. The more complicated types of RAID (anything beyond "striping" or "concatenation") can help keep the data intact even if an individual hard drive fails, though.

paragraphs: The "mean time to data loss" (MTTDL) gives the average time before a loss of data happens in a given array. Mean time to data loss of a given RAID may be higher or lower than that of its hard disks. This depends on the type of RAID used.

paragraphs: Arrays that have redundancy can recover from some failures. The "mean time to recovery" shows how long it takes until a failed array is back to its normal state. This adds both the time to replace a failed disk mechanism as well as time to re-build the array (i.e. to replicate data for redundancy).

paragraphs: The "unrecoverable bit error rate" (UBE) tells how long a disk drive will be unable to recover data after using cyclic redundancy check (CRC) codes and multiple retries.

paragraphs: There are also certain problems with the ideas or the technology behind RAID:

paragraphs: Certain RAID levels allow to extend the array by simply adding hard disks, at a later time. Information such as parity blocks is often scattered on several disks. Adding a disk to the array means that a reorganisation becomes necessary. Such a reorganisation is like a re-build of the array, it can take a long time. When this is done, the additional space may not be available yet, because both the file system on the array, and the operating system need to be told about it. Some file systems do not support to be grown after they have been created. In such a case, all the data needs to be backed up, the array needs be re-created with the new layout, and the data needs to be restored onto it.

paragraphs: Another option to add storage is to create a new array, and to let a logical volume manager handle the situation. This allows to grow almost any RAID system, even RAID1 (which by itself is limited to two disks).

paragraphs: The error correction mechanism in RAID assumes that failures of drives are independent. It is possible to calculate how often a piece of equipment can fail and to arrange the array to make data loss very improbable.

paragraphs: In practice, however, the drives were often bought together. They have roughly the same age, and have been used similarly (called "wear"). Many drives fail because of mechanical problems. The older a drive is, the more worn are its mechanical parts. Mechanical parts that are old are more likely to fail than those that are younger. This means that drive failures are no longer statistically independent. In practice, there is a chance that a second disk will also fail before the first has been recovered. This means that data loss can occur at significant rates, in practice.

paragraphs: Another problem that also occurs with RAID systems is that applications expect what is called "Atomicity": Either all of the data is written, or none is. Writing the data is known as a "transaction".

paragraphs: In RAID arrays, the new data is usually written in the place where the old data was. This has become known as "update in-place". Jim Gray, a database researcher wrote a paper in 1981 where he described this problem.

paragraphs: Very few storage systems allow "atomic write semantics". When an object is written to disk, a RAID storage device will usually be writing all copies of the object in parallel. Very often, there is only one processor responsible for writing the data. In such a case, the writes of data to the different drives will overlap. This is known as "overlapped write" or "staggered write". An error that occurs during the process of writing may therefore leave the redundant copies in different states. What is worse, it may leave the copies in neither the old nor the new state. Logging relies on the original data being either in the old or the new state, though. This permits backing out the logical change, but few storage systems provide an atomic write semantic on a RAID disk.

paragraphs: Using a battery-backed write cache can solve this problem, but only in a power failure scenario.

paragraphs: Transactional support is not present in all hardware RAID controllers. Therefore, many operating systems include it to protect against data loss during an interrupted write. Novell Netware, starting with version 3.x, included a transaction tracking system. Microsoft introduced transaction tracking via the journaling feature in NTFS. NetApp WAFL file system solves it by never updating the data in place, as does ZFS.

paragraphs: Some sectors on a hard disk may have become unreadable because of a mistake. Some RAID implementations can deal with this situation by moving the data elsewhere and marking the sector on the disk as bad. This happens at about 1 bit in 10 in enterprise-class disk drives, and 1 bit in 10 in ordinary disk drives. Disk capacities are steadily increasing. This may mean that sometimes, a RAID cannot be rebuilt, because such an error is found when the array is rebuilt after a disk failure. Certain technologies such as RAID 6 try to address this issue, but they suffer from a very high write penalty, in other words writing data becomes very slow.

paragraphs: The disk system can acknowledge the write operation as soon as the data is in the cache. It does not need to wait until the data has been physically written. However, any power outage can then mean a significant data loss of any data queued in such a cache.

paragraphs: With hardware RAID, a battery can be used to protect this cache. This often solves the problem. When the power fails, the controller can finish writing the cache when the power is back. This solution can still fail, though: the battery may have worn out, the power may have been off for too long, the disks could be moved to another controller, the controller itself could fail. Certain systems can do periodic battery checks, but these use the battery itself, and leave it in a state where it is not fully charged.

paragraphs: The disk formats on different RAID controllers are not necessarily compatible. Therefore, it may not be possible to read a RAID array on different hardware. Consequently, a non-disk hardware failure may require using identical hardware, or a backup, to recover the data.

paragraphs: This guide was taken from a thread in a RAID-related forum. This was done to help point out the advantages and disadvantages of choosing RAID. It is directed at people who want to choose RAID for either increases in performance or redundancy. It contains links to other threads in its forum containing user-generated anecdotal reviews of their RAID experiences.

paragraphs: The RAID levels used most often are RAID 0, RAID 1, and RAID 5. Suppose there is a 3 disk setup, with 3 identical disks of 1 TB each, and the probability of failure of a drive for a given timespan is 1%.


title: Leonid Brezhnev

paragraphs: Leonid Illich Brezhnev (19 December 1906 - 10 November 1982) was a leader of the Soviet Union. Born in 1906, Brezhnev was First Secretary of the Communist Party of the Soviet Union, effectively the dictator of the Soviet Union from 1964 until his death in 1982. During the Second World War, Brezhnev was a Political Commissar, supervising various military units. There, he became a friend of Nikita Khrushchev.

paragraphs: Unlike Khrushchev, the leader of the Soviet Union before him, Brezhnev did not agree with the process of destalinization, and did not support reform. Under Brezhnev, the Soviet economy mostly consisted of military spending. Because the country's resources were going to the armed forces, as they had under Joseph Stalin in wartime, consumer wants were ignored. The standard of living began to fall.

paragraphs: Brezhnev died of a heart attack on November 10, 1982.


title: Approximation

paragraphs: An approximation is a version of a piece of information that does not describe it exactly, but is close enough to be used. An approximation may be used either when the exact piece of information is not known, or when it's too long or complicated and people need something simpler.

paragraphs: For example, if you wanted to add 2.0002 and 2.0003, you can add 2 and 2, and it would be an approximation.

paragraphs: If you are left with a balance of Dollar 78.23 you might want to say you are left with 80 dollars. In mathematics, this is written using the formula_1 symbol (e.g., formula_2).

paragraphs: Archimedes used polygons to approximate a circle, and to calculate an approximation for formula_3 as shown below:


title: PhpBB

paragraphs: phpBB is a commonly used, free computer software for forums. As the name suggests, phpBB is written in PHP, with the use of one of SQL compatible databases.


title: World Health Organization

paragraphs: The World Health Organization (WHO) is part of the United Nations (UN), working on international public health, with its headquarters in Geneva, Switzerland. The WHO was established by the UN on April 7, 1948. In the previous year they had already started an epidemiology service. WHO World Health Day is celebrated on April 7.


title: Jerboa

paragraphs: A jerboa is a small desert rodent of Asia and northern Africa. It looks like a mouse, but it has a long tail and very long back legs. The jerboa moves by jumping. Jerboas have long tails, long hind legs, and short front legs.


title: Aesop

paragraphs: Aesop, or Æsop (from the Greek "Αἴσωπος" "Aisopos"), is known for his fables. He was, by tradition, a slave of African descent who lived from about 620 BC to 560 BC in Ancient Greece.

paragraphs: Aesop's Fables are still taught as moral lessons and used as subjects for entertainment, especially children's plays and cartoons. Aesop is "said" to have written thousands of fables, but none has been verified. This means we do not know whether he wrote any, or perhaps just collected them. His most famous one was perhaps "The Lion and the Mouse".

paragraphs: No writings by him survive. Tales credited to him were gathered across the centuries and in many languages. This is a storytelling tradition that continues to the present day. Many of the tales have animals and inanimate objects that speak, solve problems, and generally have human characteristics.

paragraphs: The tradition is that he was at one point freed from slavery and that he eventually died at the hands of Delphians. In fact, the doubt about his life has led some to deny his existence altogether.

paragraphs: His most famous fable is a parable of the tortoise and the hare. In this story, a rabbit challenges a tortoise to a race. The rabbit is sure of its victory and as a result, depending on the version of the story, in some way completes the race slower than the turtle. Often, the hare takes a nap or takes too many breaks. The persistent tortoise, despite being slower, wins because it persevered.

paragraphs: Aesop's Fables or "Aesopica" refers to a collection of fables credited to Aesop. Aesop's Fables has also become a blanket term for collections of brief fables, usually involving personified animals.

paragraphs: The fables remain a popular choice for moral education of children today. Many stories included in Aesop's Fables, such as "The Fox and the Grapes" (from which the idiom "sour grapes" was derived), "The Tortoise and the Hare" and "The Shepherd Boy and the Wolf" (also known as "The Boy Who Cried Wolf"), are well-known throughout the world.


title: Smell

paragraphs: The term smell may refer to one of the following articles:


title: Olfaction

paragraphs: Olfaction is the sense of smell. The sense of smell is how a human or animal notices a smell (or odour or odor) by using the nose. Many animals have better noses than people. Some animals can detect small particles in the air or sometimes water that people cannot.

paragraphs: People have special cells in the nose that can detect some chemicals. These are special nerve cells attached to the olfactory epithelium. All vertebrates have these cells. The smell is first processed by the olfactory system. The information is given to the olfactory bulb in the front of the forebrain.

paragraphs: In insects, smells are sensed by sensillum on the antennae and first processed by the antennal lobe.

paragraphs: The olfactory reception (OR) cells are neurons (nerve cells). Many tiny hair-like cilia stick out of these cells into the mucus covering the surface of the epithelium. The surface of these cilia is covered with olfactory receptors, a kind of protein.

paragraphs: There are about 1000 different genes which code for the ORs, though only about a third are functional. The rest are pseudogenes. The OR genes are the largest gene family. An odor molecule dissolves into the mucus of the olfactory epithelium and then binds to an OR. Various odor molecules bind to various ORs. The basis of the sense of smell is that different groups of scent molecules bind to different receptor cells and so fire different groups of neurons. Inside the olfactory region of the brain, the firing of neurons produces the perceived smell.

paragraphs: When the OR is activated, changes start in the cells. Positive ions come in and negative ions go out of the cells. This causes the neuron to fire an impulse (generate an action potential).


title: Teaspoon

paragraphs: A teaspoon is a spoon used for stirring tea, measuring sugar, and playing games such as spoons. They are also called flatspoons in American English. Longer teaspoons can be used to eat ice cream and other desserts, too. It is usually covered with silver or stainless steel.

paragraphs: It is also a unit of measurement, now equal to 5 millilitres, but the original customary measure was 4.93 ml.


title: Camembert

paragraphs: Camembert is a village in France. It is in Normandy. It is in the Orne "département" of the Lower Normandy region in France. It is most famous as the place where Camembert cheese originated. In 1999, 199 people lived there.


title: Camembert cheese

paragraphs: Camembert cheese, more generally known as Camembert, is a French soft cheese. It originated in the village of Camembert in Normandy. Since 1983, the name "Camembert de Normandie" has been protected as Appellation d'Origine controlée (AOC).

paragraphs: Camembert is made from unpasteurized cow's milk, and is ripened by the moulds "Penicillium candida" and "Penicillium camemberti" for at least three weeks. It is produced in small rounds, about 250 grams in weight, which are wrapped in paper and boxed in thin wooden boxes.

paragraphs: When fresh, it is quite crumbly and relatively hard, but it characteristically ripens and becomes more runny and strongly flavoured as it ages.

paragraphs: Camembert can be used in many dishes, but it is popularly eaten uncooked on bread or with wine or meat, to enjoy the subtle flavour and texture which do not survive heating.

paragraphs: Camembert was reputedly invented in 1791 by Marie Harel, a farmer from Normandy. However, the origin of the cheese we know today as camembert is more likely to rest with the beginnings of the industrialisation of the cheese-making process at the end of the 19th century. In 1890, an engineer, M. Ridel invented the wooden box which was used to carry the cheese and helped to send it for longer distances, in particular to America where it became very popular. These boxes are still used today.

paragraphs: Before fungi were properly understood, the colour of Camembert rind was a matter of chance, most commonly blue-grey, with brown spots. From the early 20th century onwards the rind has been more commonly pure white, but it was not until the mid-1970s that pure white became standard.

paragraphs: The cheese was famously issued to French troops in the First World War, becoming firmly fixed in the French popular culture as a result. It has many other roles in French culture, literature and history. It is now internationally known, and many local varieties are made around the world.

paragraphs: The cheese is said to have inspired Salvador Dalí to create his famous painting, "The Persistence of Memory". Its "melting" watches were inspired by the sight of a melting wheel of over-ripe Camembert.

paragraphs: The Camembert de Normandie was granted a protected designation of origin in 1992 after the original AOC in 1983.

paragraphs: "Camembert: A National Myth" by Pierre Boisard claims that Camembert was one of the first globalised, homogenised and standardised foods.


title: Childbirth

paragraphs: Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies leaves the uterus by passing through the vagina or by Caesarean section. In 2015, there were about 135 million births globally.

paragraphs: About 15 million were born before 37 weeks of gestation, while between 3 and 12 percent were born after 42 weeks.


title: Shiva

paragraphs: Shiva or Mahadeva is one of the three main gods in Hinduism. Shiva is causeless auspiciousness. An embodiment of ultimate space of enlightenment. He assumed human form to guide humans in the past and thus is known as Adhiguru (first guru).

paragraphs: His space of enlightenment is what all spiritual seekers aspire for. All enlightened masters live in this space of Shiva. Shiva is known as the destroyer god because he removes all evil from the world. His wife is the goddess Parvati or Devi Durga.

paragraphs: According to Hindu legend, he has a blue neck because he swallowed a poison in order to save the universe. He has three eyes, the third eye is on his forehead. Shiva is one-third of the Hindu trimurti including Brahma and Vishnu. Lord Shiva lives in the Mount Kailash with his two sons Kartikeya and Ganesha who is known as the Remover of Obstacles. There is a statue of Shiva in Bangalore which is a great tourist attraction.

paragraphs: An ancient sculpture of Shiva at the Elephanta Caves, Maharashtra

paragraphs: In the earliest of the vedic texts, the word "Shiva" means Auspicious, Sacred. It does not relate to any deity, but refers to the quality of being sacred and auspicious.

paragraphs: In later vedic texts, Shiva becomes a deity. Shiva is also called as "Brahman", the supreme universal consciousness. The word "shivo'ham" translates as "I am Shiva", conveying that one's consciousness is where the lord resides, uniting it with the supreme "transcendence". In Tamil, he was called by different names other than Sivan. Nataraja (Dancing form of Shiva), Rudra (Enraged form of Shiva), and Dhakshinamoorthy (Yoga form of Shiva). Nataraja is the only form of Shiva worshipped in a human figure format. Elsewhere he is worshipped in Lingam figure. Pancha Bootha temples are located in south India. Pancha Bhoota Stalam refers to five temples dedicated to Shiva. Tamil literature is enriched by Shiva devotees called 63 Nayanmars (Nayanars).

paragraphs: A sculpture of Shiva with Moustache at Archaeological Museum, Goa

paragraphs: The Sanskrit word ""śiva"" (Devanagari: शिव, also transliterated as "shiva") means, states Monier Monier-Williams, "auspicious, propitious, gracious, benign, kind, benevolent, friendly". The roots of "śiva" in folk etymology are "śī" which means "in whom all things lie, pervasiveness" and "va" which means "embodiment of grace".

paragraphs: The word Shiva is used as an adjective in the Rig Veda (approximately 1700–1100 BC), as an epithet for several Rigvedic deities, including Rudra. The term Shiva also connotes "liberation, final emancipation" and "the auspicious one", this adjective sense of usage is addressed to many deities in Vedic layers of literature. The term evolved from the Vedic "Rudra-Shiva" to the noun "Shiva" in the Epics and the Puranas, as an auspicious deity who is the "creator, reproducer and dissolver".

paragraphs: Sharva, sharabha presents another etymology with the Sanskrit root ""śarv"-", which means "to injure" or "to kill", interprets the name to connote "one who can kill the forces of darkness".

paragraphs: The Sanskrit word 'śaiva' means "relating to the god Shiva", and this term is the Sanskrit name both for one of the principal sects of Hinduism and for a member of that sect. It is used as an adjective to characterize certain beliefs and practices, such as Shaivism.

paragraphs: The "Vishnu sahasranama" interprets "Shiva" to have multiple meanings: "The Pure One", and "the One who is not affected by three Guṇas of Prakṛti (Sattva, Rajas, and Tamas)".

paragraphs: Shiva is known by many names such as Viswanatha (lord of the universe), Mahadeva, Mahandeo, Mahasu, Mahesha, Maheshvara, Shankara, Shambhu, Rudra, Hara, Trilochana, Devendra (chief of the gods), Neelakanta, Subhankara, Trilokinatha (lord of the three realms), and Ghrneshwar (lord of compassion). The highest reverence for Shiva in Shaivism is reflected in his epithets 'Mahādeva' ("Great god"; 'mahā' "Great" and "deva" "god"), 'Maheśvara' ("Great Lord"; 'mahā' "great" and 'īśvara' "lord"), and 'Parameśvara' ("Supreme Lord").

paragraphs: Sahasranama are medieval Indian texts that list a thousand names derived from aspects and epithets of a deity. There are at least eight different versions of the "Shiva Sahasranama", devotional hymns ("stotras") listing many names of Shiva. The version appearing in Book 13 ("Anuśāsanaparvan") of the "Mahabharata" provides one such list. Shiva also has "Dasha-Sahasranamas" (10,000 names) that are found in the "Mahanyasa". The "Shri Rudram Chamakam", also known as the "Śatarudriya", is a devotional hymn to Shiva hailing him by many names.

paragraphs: The Shiva-related tradition is a major part of Hinduism, found all over the Indian subcontinent, such as India, Nepal, Sri Lanka, and Southeast Asia, such as Bali, Indonesia. Scholars have interpreted early prehistoric paintings at the Bhimbetka rock shelters, carbon dated to be from pre-10,000 BCE period, as Shiva dancing, Shiva's trident, and his mount Nandi. Rock paintings from Bhimbetka, depicting a figure with a trishul, have been described as Nataraja by Erwin Neumayer, who dates them to the mesolithic.

paragraphs: Seal discovered during excavation of the Indus Valley archaeological site in the Indus Valley has drawn attention as a possible representation of a "yogi" or "proto-Shiva" figure.

paragraphs: Of several Indus valley seals that show animals, one seal that has attracted attention shows a large central figure, either horned or wearing a horned headdress and possibly ithyphallic, seated in a posture reminiscent of the Lotus position, surrounded by animals. This figure was named by early excavators of Mohenjo-daro as "Pashupati" (Lord of Animals, Sanskrit 'paśupati'), an epithet of the later Hindu deities Shiva and Rudra.

paragraphs: Sir John Marshall and others suggested that this figure is a prototype of Shiva, with three faces, seated in a "yoga posture" with the knees out and feet joined. Semi-circular shapes on the head were interpreted as two horns. Scholars such as Gavin Flood, John Keay and Doris Meth Srinivasan have expressed doubts about this suggestion.

paragraphs: Gavin Flood states that it is not clear from the seal that the figure has three faces, is seated in a yoga posture, or even that the shape is intended to represent a human figure. He characterizes these views as "speculative", but adds that it is nevertheless possible that there are echoes of Shaiva iconographic themes, such as half-moon shapes resembling the horns of a bull. John Keay writes that "he may indeed be an early manifestation of Lord Shiva as Pashu-pati", but a couple of his specialties of this figure does not match with Rudra. Writing in 1997, Srinivasan interprets what John Marshall interpreted as facial as not human but more bovine, possibly a divine buffalo-man.

paragraphs: The interpretation of the seal continues to be disputed. McEvilley, for example, states that it is not possible to "account for this posture outside the yogic account". Asko Parpola states that other archaeological finds such as the early Elamite seals dated to 3000-2750 BCE show similar figures and these have been interpreted as "seated bull" and not a yogi, and the bovine interpretation is likely more accurate. Gregory L. Possehl in 2002, associated it with the water buffalo, and concluded that while it would be appropriate to recognize the figure as a deity, and its posture as one of ritual discipline, regarding it as a proto-Shiva would "go too far".

paragraphs: The Vedic literature refers to a minor atmospheric deity, with fearsome powers called Rudra. The Rigveda, for example, has 3 out of 1,028 hymns dedicated to Rudra, and he finds occasional mention in other hymns of the same text. The term Shiva also appears in the Rigveda, but simply as an epithet, that means "kind, auspicious", one of the adjectives used to describe many different Vedic deities. While fierce ruthless natural phenomenon and storm-related Rudra is feared in the hymns of the Rigveda, the beneficial rains he brings are welcomed as Shiva aspect of him. This healing, nurturing, life-enabling aspect emerges in the Vedas as Rudra-Shiva, and in post-Vedic literature ultimately as Shiva who combines the destructive and constructive powers, the terrific and the gentle, as the ultimate recycler and rejuvenator of all existence.

paragraphs: The similarities between the iconography and theologies of Shiva with Greek and European deities have led to proposals for an Indo-European link for Shiva, or lateral exchanges with ancient central Asian cultures. His contrasting aspects such as being terrifying or blissful depending on the situation, are similar to those of the Greek god Dionysus, as are their iconic associations with bull, snakes, anger, bravery, dancing and carefree life. The ancient Greek texts of the time of Alexander the Great call Shiva as "Indian Dionysus", or alternatively call Dionysus as ""god of the Orient"". Similarly, the use of phallic symbol as an icon for Shiva is also found for Irish, Nordic, Greek (Dionysus) and Roman deities, as was the idea of this aniconic column linking heaven and earth among early Indo-Aryans, states Roger Woodward. Others contest such proposals, and suggest Shiva to have emerged from indigenous pre-Aryan tribal origins.

paragraphs: Three-headed Shiva, Gandhara, 2nd century AD

paragraphs: Shiva as we know him today shares many features with the Vedic god Rudra, and both Shiva and Rudra are viewed as the same personality in Hindu scriptures. The two names are used synonymously. Rudra, the god of the roaring storm, is usually portrayed in accordance with the element he represents as a fierce, destructive deity.

paragraphs: The oldest surviving text of Hinduism is the Rig Veda, which is dated to between 1700 and 1100 BC based on linguistic and philological evidence. A god named Rudra is mentioned in the Rig Veda. The name Rudra is still used as a name for Shiva. In RV 2.33, he is described as the "Father of the Rudras", a group of storm gods.

paragraphs: The hymn 10.92 of the Rigveda states that deity Rudra has two natures, one wild and cruel (Rudra), another that is kind and tranquil (Shiva). The Vedic texts do not mention bull or any animal as the transport vehicle ("vahana") of Rudra or other deities. However, post-Vedic texts such as the Mahabharata and the Puranas state the Nandi bull, the Indian zebu, in particular, as the vehicle of Rudra and of Shiva, thereby unmistakably linking them as same.

paragraphs: Rudra and Agni have a close relationship. The identification between Agni and Rudra in the Vedic literature was an important factor in the process of Rudra's gradual development into the later character as Rudra-Shiva. The identification of Agni with Rudra is explicitly noted in the "Nirukta", an important early text on etymology, which says, "Agni is also called Rudra." The interconnections between the two deities are complex, and according to Stella Kramrisch:The fire myth of "Rudra-Śiva" plays on the whole gamut of fire, valuing all its potentialities and phases, from conflagration to illumination.In the "Śatarudrīya", some epithets of Rudra, such as "Sasipañjara" ("Of golden red hue as of flame") and "Tivaṣīmati" ("Flaming bright"), suggest a fusing of the two deities. Agni is said to be a bull, and Lord Shiva possesses a bull as his vehicle, Nandi. The horns of Agni, who is sometimes characterized as a bull, are mentioned. In medieval sculpture, both Agni and the form of Shiva known as Bhairava have flaming hair as a special feature.

paragraphs: Coin of the Kushan Empire (1st-century BCE to 2nd-century CE). The right image has been interpreted as Shiva with trident and bull.

paragraphs: According to Wendy Doniger, the Puranic Shiva is a continuation of the Vedic Indra. Doniger gives several reasons for her hypothesis. Both are associated with mountains, rivers, male fertility, fierceness, fearlessness, warfare, the transgression of established mores, the Aum sound, the Supreme Self. In the Rig Veda the term 'śiva' is used to refer to Indra. (2.20.3, 6.45.17, and 8.93.3.) Indra, like Shiva, is likened to a bull. In the Rig Veda, Rudra is the father of the Maruts, but he is never associated with their warlike exploits as is Indra.

paragraphs: The Vedic beliefs and practices of the pre-classical era were closely related to the hypothesised Proto-Indo-European religion, and the pre-Islamic Indo-Iranian religion. The earliest iconic artworks of Shiva may be from Gandhara and northwest parts of ancient India. There is some uncertainty as the artwork that has survived is damaged and they show some overlap with meditative Buddha-related artwork, but the presence of Shiva's trident and phallic symbolism in this art suggests it was likely Shiva. Numismatics research suggests that numerous coins of the ancient Kushan Empire that have survived, were images of a god who is probably Shiva. The Shiva in Kushan coins is referred to as Oesho of unclear etymology and origins, but the simultaneous presence of Indra and Shiva in the Kushan era artwork suggest that they were revered deities by the start of the Kushan Empire.

paragraphs: The texts and artwork of Jainism show Indra as a dancer, although not identical generally resembling the dancing Shiva artwork found in Hinduism, particularly in their respective mudras. For example, in the Jain caves at Ellora, extensive carvings show dancing Indra next to the images of Tirthankaras in a manner similar to Shiva Nataraja. The similarities in the dance iconography suggests that there may be a link between ancient Indra and Shiva.

paragraphs: Rudra's evolution from a minor Vedic deity to a supreme being is first evidenced in the "Shvetashvatara Upanishad" (400–200 BC), according to Gavin Flood. Prior to it, the Upanishadic literature is monistic, and the "Shvetashvatara" text presents the earliest seeds of theistic devotion to Rudra-Shiva. Here Rudra-Shiva is identified as the creator of the cosmos and liberator of souls from the birth-rebirth cycle. The period of 200 BC to 100 AD also marks the beginning of the Shaiva tradition focused on the worship of Shiva as evidenced in other literature of this period. Shaiva devotees and ascetics are mentioned in Patanjali's "Mahābhāṣya" (2nd-century BC) and in the "Mahabharata". Other scholars such as Robert Hume and Doris Srinivasan state that the "Shvetashvatara Upanishad" presents pluralism, pantheism, or henotheism, rather than being a text just on Shiva theism.

paragraphs: The Shaiva Upanishads are a group of 14 minor Upanishads of Hinduism variously dated from the last centuries of the 1st millennium BCE through the 17th century. These extol Shiva as the metaphysical unchanging reality Brahman and the Atman (soul, self), and include sections about rites and symbolisms related to Shiva.

paragraphs: A few texts such as "Atharvashiras Upanishad" mention Rudra, and assert all gods are Rudra, everyone and everything is Rudra, and Rudra is the principle found in all things, their highest goal, the innermost essence of all reality that is visible or invisible. The "Kaivalya Upanishad" similarly, states Paul Deussen – a German Indologist and professor of Philosophy, describes the self-realized man as who "feels himself only as the one divine essence that lives in all", who feels identity of his and everyone's consciousness with Shiva (highest Atman), who has found this highest Atman within, in the depths of his heart.

paragraphs: The Shaiva Puranas, particularly the Shiva Purana and the Linga Purana, present the various aspects of Shiva, mythologies, cosmology and pilgrimage ("Tirtha") associated with him. The Shiva-related Tantra literature, composed between the 8th and 11th centuries, are regarded in devotional dualistic Shaivism as Sruti. Dualistic Shaiva Agamas which consider soul within each living being and Shiva as two separate realities (dualism, "dvaita"), are the foundational texts for Shaiva Siddhanta. Other Shaiva Agamas teach that these are one reality (monism, "advaita"), and that Shiva is the soul, the perfection and truth within each living being. In Shiva related sub-traditions, there are ten dualistic Agama texts, eighteen qualified monism-cum-dualism Agama texts and sixty-four monism Agama texts.

paragraphs: Shiva-related literature developed extensively across India in the 1st millennium CE and through the 13th century, particularly in Kashmir and Tamil Shaiva traditions. The monist Shiva literature posit absolute oneness, that is Shiva is within every man and woman, Shiva is within every living being, Shiva is present everywhere in the world including all non-living being, and there is no spiritual difference between life, matter, man and Shiva. The various dualistic and monist Shiva-related ideas were welcomed in medieval southeast Asia, inspiring numerous Shiva-related temples, artwork and texts in Indonesia, Myanmar, Cambodia, Laos, Vietnam, Thailand and Malaysia, with syncretic integration of local pre-existing theologies.

paragraphs: The figure of Shiva as we know him today may be an amalgamation of various older deities into a single figure. How the persona of Shiva converged as a composite deity is not understood, a challenge to trace and has attracted much speculation. According to Vijay Nath, for example:Vishnu and Siva [...] began to absorb countless local cults and deities within their folds. The latter were either taken to represent the multiple facets of the same god or else were supposed to denote different forms and appellations by which the god came to be known and worshipped. [...] Siva became identified with countless local cults by the sheer suffixing of "Isa" or "Isvara" to the name of the local deity, e.g., Bhutesvara, Hatakesvara, Chandesvara."An example of assimilation took place in Maharashtra, where a regional deity named Khandoba is a patron deity of farming and herding castes. The foremost center of worship of Khandoba in Maharashtra is in Jejuri. Khandoba has been assimilated as a form of Shiva himself, in which case he is worshipped in the form of a lingam. Khandoba's varied associations also include an identification with Surya and Karttikeya.

paragraphs: Lingodbhava is a Shaiva sectarian icon where Shiva is depicted rising from the Lingam (an infinite fiery pillar) that narrates how Shiva is the foremost of the Trimurti; Brahma and Vishnu are depicted bowing to Lingodbhava Shiva in the centre.

paragraphs: Main articles: Shaivism and History of Shaivism

paragraphs: Shaivism is one of the four major sects of Hinduism, the others being Vaishnavism, Shaktism and the Smarta Tradition. Followers of Shaivism, called "Shaivas", revere Shiva as the Supreme Being. Shaivas believe that Shiva is All and in all, the creator, preserver, destroyer, revealer and concealer of all that is. He is not only the creator in Shaivism, but he is also the creation that results from him, he is everything and everywhere. Shiva is the primal soul, the pure consciousness and Absolute Reality in the Shaiva traditions.

paragraphs: The Shaivism theology is broadly grouped into two: the popular theology influenced by Shiva-Rudra in the Vedas, Epics and the Puranas; and the esoteric theology influenced by the Shiva and Shakti-related Tantra texts. The Vedic-Brahmanic Shiva theology includes both monist ("Advaita") and devotional traditions ("Dvaita") such as Tamil Shaiva Siddhanta and Lingayatism with temples featuring items such as linga, Shiva-Parvati iconography, bull Nandi within the premises, relief artwork showing mythologies and aspects of Shiva.

paragraphs: The Tantric Shiva tradition ignored the mythologies and Puranas related to Shiva, and depending on the sub-school developed a variety of practices. For example, historical records suggest the tantric Kapalikas (literally, the 'skull-men') co-existed with and shared many Vajrayana Buddhist rituals, engaged in esoteric practices that revered Shiva and Shakti wearing skulls, begged with empty skulls, used meat, alcohol, and sexuality as a part of ritual. In contrast, the esoteric tradition within Kashmir Shaivism has featured the "Krama" and "Trika" sub-traditions. The Krama sub-tradition focussed on esoteric rituals around Shiva-Kali pair. The Trika sub-tradition developed a theology of triads involving Shiva, combined it with an ascetic lifestyle focusing on personal Shiva in the pursuit of monistic self liberation.

paragraphs: The Vaishnava (Vishnu-oriented) literature acknowledges and discusses Shiva. Like Shaiva literature that presents Shiva as supreme, the Vaishnava literature presents Vishnu as supreme. However, both traditions are pluralistic and revere both Shiva and Vishnu (along with Devi), their texts do not show exclusivism, and Vaishnava texts such as the "Bhagavata Purana" while praising Krishna as the Ultimate Reality, also present Shiva and Shakti as a personalized form an equivalent to the same Ultimate Reality. The texts of Shaivism tradition similarly praise Vishnu. The Skanda Purana, for example, states:Vishnu is no one but Shiva, and he who is called Shiva is but identical with Vishnu.

paragraphs: — Mythologies of both traditions include legends about who is superior, about Shiva paying homage to Vishnu, and Vishnu paying homage to Shiva. However, in texts and artwork of either tradition, the mutual salutes are symbolism for complementarity. The Mahabharata declares the unchanging Ultimate Reality (Brahman) to be identical to Shiva and to Vishnu, that Vishnu is the highest manifestation of Shiva, and Shiva is the highest manifestation of Vishnu.

paragraphs: Ardhanarishvara sculpture, Khajuraho, depicting Shiva with goddess Parvati as his equal half. In the Ardhanarisvara concept, the icon is presented as half-man and half woman.

paragraphs: The goddess-oriented Shakti tradition of Hinduism is based on the premise that the Supreme Principle and the Ultimate Reality called Brahman is female (Devi), but it treats the male as her equal and complementary partner. This partner is Shiva.

paragraphs: The earliest evidence of the tradition of reverence for the feminine with Rudra-Shiva context, is found in the Hindu scripture "Rigveda", in a hymn called the Devi Sukta:3. I am ruler, assembler of goods, observer foremost among those deserving the sacrifice.

paragraphs: Me have the gods distributed in many places—so that I have many stations and cause many things to enter (me).

paragraphs: 4. Through me he eats food—whoever sees, whoever breathes, whoever hears what is spoken.

paragraphs: Without thinking about it, they live on me. Listen, o you who are listened to: it’s a trustworthy thing I tell you.

paragraphs: 5. Just I myself say this, savored by gods and men:

paragraphs: "Whom I love, just him I make formidable, him a formulator, him a seer,

paragraphs: 6. I stretch the bow for Rudra, for his arrow to smash the hater of the

paragraphs: I make combat for the people. I have entered Heaven and Earth.

paragraphs: 7. I give birth to Father (Heaven) on his (own) head [Agni]; my womb is in the waters, in the sea.

paragraphs: Thence I spread forth across all worlds, and yonder heaven with its height I touch.

paragraphs: 8. I, just like the wind, blow forth, grasping at all worlds,

paragraphs: beyond heaven, beyond this earth here—of such size in my greatness

paragraphs: — The "Devi Upanishad" in its explanation of the theology of Shaktism, mentions and praises Shiva such as in its verse 19. Shiva, along with Vishnu, is a revered god in the "Devi Mahatmya", a text of Shaktism considered by the tradition to be as important as the "Bhagavad Gita". The Ardhanarisvara concept co-mingles god Shiva and goddess Shakti by presenting an icon that is half-man and half woman, a representation and theme of union found in many Hindu texts and temples.

paragraphs: Oleograph by Raja Ravi Varma depicting a Shiva-centric Panchayatana. A bearded Shiva sits in the centre with his wife Parvati and their infant son Ganesha; surrounded by (clockwise from left upper corner) Ganesha, Devi, Vishnu, and Surya. Shiva's mount is the bull Nandi below Shiva.

paragraphs: In the Smarta tradition of Hinduism, Shiva is a part of its Panchayatana puja. This practice consists of the use of icons or anicons of five deities considered equivalent, set in a quincunx pattern. Shiva is one of the five deities, others being Vishnu, Devi (such as Parvati), Surya and Ganesha or Skanda or any personal god of devotee's preference (Ishta Devata).

paragraphs: Philosophically, the Smarta tradition emphasizes that all idols (murti) are icons to help focus on and visualize aspects of Brahman, rather than distinct beings. The ultimate goal in this practice is to transition past the use of icons, recognize the Absolute symbolized by the icons, on the path to realizing the nondual identity of one's Atman (soul, self) and the Brahman. Popularized by Adi Shankara, many Panchayatana mandalas and temples have been uncovered that are from the Gupta Empire period, and one Panchayatana set from the village of Nand (about 24 kilometers from Ajmer) has been dated to belong to the Kushan Empire era (pre-300 CE). The Kushan period set includes Shiva, Vishnu, Surya, Brahma and one deity whose identity is unclear.

paragraphs: Adiyogi Shiva statue, recognized by the "Guinness World Records" as the "Largest Bust Sculpture” in the world; the statue is for inspiring and promoting yoga, and is named "Adiyogi", which means "the first yogi", because Shiva is known as the originator of yoga.

paragraphs: Shiva is considered the Great Yogi who is totally absorbed in himself – the transcendental reality. He is the Lord of Yogis, and the teacher of Yoga to sages. As Shiva Dakshinamurthi, states Stella Kramrisch, he is the supreme guru who "teaches in silence the oneness of one's innermost self ("atman") with the ultimate reality ("brahman")."

paragraphs: The theory and practice of Yoga, in different styles, has been a part of all major traditions of Hinduism, and Shiva has been the patron or spokesperson in numerous Hindu Yoga texts. These contain the philosophy and techniques for Yoga. These ideas are estimated to be from or after the late centuries of the 1st millennium CE, and have survived as Yoga texts such as the "Isvara Gita" (literally, 'Shiva's song'), which Andrew Nicholson – a professor of Hinduism and Indian Intellectual History – states have had "a profound and lasting influence on the development of Hinduism".

paragraphs: Other famed Shiva-related texts influenced Hatha Yoga, integrated monistic ("Advaita Vedanta") ideas with Yoga philosophy and inspired the theoretical development of Indian classical dance. These include the "Shiva Sutras", the "Shiva Samhita", and those by the scholars of Kashmir Shaivism such as the 10th-century scholar Abhinavagupta. Abhinavagupta writes in his notes on the relevance of ideas related to Shiva and Yoga, by stating that "people, occupied as they are with their own affairs, normally do nothing for others", and Shiva and Yoga spirituality helps one look beyond, understand interconnectedness, and thus benefit both the individual and the world towards a more blissful state of existence.

paragraphs: An art depiction of the Trimurti, with Shiva depicted on the right, at the Hoysaleswara temple in Halebidu.

paragraphs: The Trimurti is a concept in Hinduism in which the cosmic functions of creation, maintenance, and destruction are personified by the forms of Brahma the creator, Vishnu the maintainer or preserver and Shiva the destroyer or transformer. These three deities have been called "the Hindu triad" or the "Great Trinity". However, the ancient and medieval texts of Hinduism feature many triads of gods and goddesses, some of which do not include Shiva.

paragraphs: Shiva with Parvati. Shiva is depicted three-eyed, the Ganges flowing through his matted hair, wearing ornaments of serpents and a skull garland, covered in ashes, and seated on a tiger skin

paragraphs: A seated Shiva holds an axe and deer in his hands.

paragraphs: According to Gavin Flood, "Shiva is a god of ambiguity and paradox," whose attributes include opposing themes. The ambivalent nature of this deity is apparent in some of his names and the stories told about him.

paragraphs: Shiva is represented in his many aspects. Left: Bhairava icon of the fierce form of Shiva, from 17th/18th century Nepal; Right: Shiva as a meditating yogi in Rishikesh.

paragraphs: In Yajurveda, two contrary sets of attributes for both malignant or terrifying (Sanskrit: 'rudra') and benign or auspicious (Sanskrit: 'śiva') forms can be found, leading Chakravarti to conclude that "all the basic elements which created the complex Rudra-Śiva sect of later ages are to be found here". In the Mahabharata, Shiva is depicted as "the standard of invincibility, might, and terror", as well as a figure of honor, delight, and brilliance.

paragraphs: The duality of Shiva's fearful and auspicious attributes appears in contrasted names. The name Rudra reflects Shiva's fearsome aspects. According to traditional etymologies, the Sanskrit name "Rudra" is derived from the root "rud-", which means "to cry, howl". Stella Kramrisch notes a different etymology connected with the adjectival form "raudra", which means "wild, of "rudra" nature", and translates the name "Rudra" as "the wild one" or "the fierce god". R. K. Sharma follows this alternate etymology and translates the name as "terrible". Hara is an important name that occurs three times in the Anushasanaparvan version of the "Shiva sahasranama", where it is translated in different ways each time it occurs, following a commentorial tradition of not repeating an interpretation. Sharma translates the three as "one who captivates", "one who consolidates", and "one who destroys". Kramrisch translates it as "the ravisher". Another of Shiva's fearsome forms is as "Kāla" "time" and "Mahākāla" "great time", which ultimately destroys all things. The name "Kāla" appears in the "Shiva Sahasranama", where it is translated by Ram Karan Sharma as "(the Supreme Lord of) Time". Bhairava "terrible" or "frightful" is a fierce form associated with annihilation. In contrast, the name "Śaṇkara", "beneficent" or "conferring happiness" reflects his benign form. This name was adopted by the great Vedanta philosopher Adi Shankara (c. 788–820), who is also known as Shankaracharya. The name "Śambhu" (Sanskrit: शम्भु swam-on its own; bhu-burn/shine) "self-shining/ shining on its own", also reflects this benign aspect.

paragraphs: Shiva is depicted both as an ascetic yogi, and as a householder with goddess Parvati.

paragraphs: Shiva is depicted as both an ascetic yogi and as a householder (grihasta), roles which have been traditionally mutually exclusive in Hindu society. When depicted as a yogi, he may be shown sitting and meditating. His epithet Mahāyogi ("the great Yogi: 'Mahā' = "great", "Yogi" = "one who practices Yoga") refers to his association with yoga. While Vedic religion was conceived mainly in terms of sacrifice, it was during the Epic period that the concepts of tapas, yoga, and asceticism became more important, and the depiction of Shiva as an ascetic sitting in philosophical isolation reflects these later concepts.

paragraphs: As a family man and householder, he has a wife, Parvati and two sons, Ganesha and Kartikeya. His epithet "Umāpati" ("The husband of "Umā"") refers to this idea, and Sharma notes that two other variants of this name that mean the same thing, "Umākānta" and "Umādhava", also appear in the "sahasranama". "Umā" in epic literature is known by many names, including the benign "Pārvatī". She is identified with Devi, the Divine Mother; Shakti (divine energy) as well as goddesses like Tripura Sundari, Durga, Kali, Kamakshi and Minakshi. The consorts of Shiva are the source of his creative energy. They represent the dynamic extension of Shiva onto this universe. His son Ganesha is worshipped throughout India and Nepal as the Remover of Obstacles, Lord of Beginnings and Lord of Obstacles. Kartikeya is worshipped in South India (especially in Tamil Nadu, Kerala and Karnataka) by the names Subrahmanya, Subrahmanyan, Shanmughan, Swaminathan and Murugan, and in Northern India by the names Skanda, Kumara, or Karttikeya.

paragraphs: Some regional deities are also identified as Shiva's children. As one story goes, Shiva is enticed by the beauty and charm of Mohini, Vishnu's female avatar, and procreates with her. As a result of this union, Shasta – identified with regional deities Ayyappan and Aiyanar – is born. In outskirts of Ernakulam in Kerala, a deity named Vishnumaya is stated to be offspring of Shiva and invoked in local exorcism rites, but this deity is not traceable in Hindu pantheon and is possibly a local tradition with "vaguely Chinese" style rituals, states Saletore. In some traditions, Shiva has daughters like the serpent-goddess Manasa and Ashokasundari. According to Doniger, two regional stories depict demons Andhaka and Jalandhara as the children of Shiva who war with him, and are later destroyed by Shiva.

paragraphs: Chola dynasty statue depicting Shiva dancing as Nataraja (Los Angeles County Museum of Art).

paragraphs: The depiction of Shiva as Nataraja (Sanskrit: 'naṭarāja', "Lord of Dance") is popular. The names Nartaka ("dancer") and Nityanarta ("eternal dancer") appear in the Shiva Sahasranama. His association with dance and also with music is prominent in the Puranic period. In addition to the specific iconographic form known as Nataraja, various other types of dancing forms (Sanskrit: 'nṛtyamūrti') are found in all parts of India, with many well-defined varieties in Tamil Nadu in particular. The two most common forms of the dance are the Tandava, which later came to denote the powerful and masculine dance as Kala-Mahakala associated with the destruction of the world. When it requires the world or universe to be destroyed, Shiva does it by the Tandava, and Lasya, which is graceful and delicate and expresses emotions on a gentle level and is considered the feminine dance attributed to the goddess Parvati. "Lasya" is regarded as the female counterpart of "Tandava". The "Tandava"-"Lasya" dances are associated with the destruction-creation of the world.

paragraphs: Dakshinamurthy "("Dakṣiṇāmūrti")" literally describes a form ('mūrti') of Shiva facing south ('dakṣiṇa'). This form represents Shiva in his aspect as a teacher of yoga, music, and wisdom and giving exposition on the "shastras". This iconographic form for depicting Shiva in Indian art is mostly from Tamil Nadu. Elements of this motif can include Shiva seated upon a deer-throne and surrounded by sages who are receiving his instruction.

paragraphs: An iconographic representation of Shiva called Ardhanarishvara ('Ardhanārīśvara') shows him with one half of the body as male and the other half as female. According to Ellen Goldberg, the traditional Sanskrit name for this form is best translated as "the lord who is half woman", not as "half-man, half-woman".

paragraphs: Shiva is often depicted as an archer in the act of destroying the triple fortresses, "Tripura", of the Asuras. Shiva's name Tripurantaka ('Tripurāntaka'), "ender of Tripura", refers to this important story.

paragraphs: Apart from anthropomorphic images of Shiva, he is also represented in aniconic form of a lingam. These are depicted in various designs. One common form is the shape of a vertical rounded column in the centre of a lipped, disk-shaped object, the "yoni", symbolism for the goddess Shakti. In Shiva temples, the "linga" is typically present in its sanctum sanctorum and is the focus of votary offerings such as milk, water, flower petals, fruit, fresh leaves, and rice. According to Monier Williams and Yudit Greenberg, "linga" literally means 'mark, sign or emblem', and also refers to a "mark or sign from which the existence of something else can be reliably inferred". It implies the regenerative divine energy innate in nature, symbolized by Shiva. Some scholars, such as Wendy Doniger, view "linga" merely as an erotic phallic symbol, although this interpretation is criticized by others, including Swami Vivekananda, Sivananda Saraswati, and S. N. Balagangadhara. According to Moriz Winternitz, the "linga" in the Shiva tradition is "only a symbol of the productive and creative principle of nature as embodied in Shiva", and it has no historical trace in any obscene phallic cult.

paragraphs: The worship of the lingam originated from the famous hymn in the "Atharva-Veda Samhitâ" sung in praise of the "Yupa-Stambha", the sacrificial post. In that hymn, a description is found of the beginningless and endless "Stambha" or "Skambha", and it is shown that the said "Skambha" is put in place of the eternal Brahman. Just as the Yajna (sacrificial) fire, its smoke, ashes, and flames, the "Soma" plant, and the ox that used to carry on its back the wood for the Vedic sacrifice gave place to the conceptions of the brightness of Shiva's body, his tawny matted hair, his blue throat, and the riding on the bull of the Shiva, the "Yupa-Skambha" gave place in time to the "Shiva-Linga". In the text "Linga Purana", the same hymn is expanded in the shape of stories, meant to establish the glory of the great Stambha and the superiority of Shiva as Mahadeva.

paragraphs: The oldest known archaeological "linga" as an icon of Shiva is the Gudimallam lingam from 3rd-century BCE. In Shaivism pilgrimage tradition, twelve major temples of Shiva are called Jyotirlinga, which means "linga of light", and these are located across India.

paragraphs: The 10th century five headed Shiva, Sadashiva, Cambodia.

paragraphs: Five is a sacred number for Shiva. One of his most important mantras has five syllables ("namaḥ śivāya").

paragraphs: Shiva's body is said to consist of five mantras, called the "pañcabrahmans". As forms of God, each of these have their own names and distinct iconography:

paragraphs: These are represented as the five faces of Shiva and are associated in various texts with the five elements, the five senses, the five organs of perception, and the five organs of action. Doctrinal differences and, possibly, errors in transmission, have resulted in some differences between texts in details of how these five forms are linked with various attributes. The overall meaning of these associations is summarized by Stella Kramrisch:Through these transcendent categories, Śiva, the ultimate reality, becomes the efficient and material cause of all that exists.According to the "Pañcabrahma Upanishad":One should know all things of the phenomenal world as of a fivefold character, for the reason that the eternal verity of "Śiva" is of the character of the fivefold Brahman. ("Pañcabrahma Upanishad" 31)

paragraphs: Puranic scriptures contain occasional references to "ansh" – literally 'portion, or avatars of Shiva', but the idea of Shiva avatars is not universally accepted in Saivism. The Linga Purana mentions twenty-eight forms of Shiva which are sometimes seen as avatars, however such mention is unusual and the avatars of Shiva is relatively rare in Shaivism compared to the well emphasized concept of Vishnu avatars in Vaishnavism. Some Vaishnava literature reverentially link Shiva to characters in its mythologies. For example, in the "Hanuman Chalisa", Hanuman is identified as the eleventh avatar of Shiva. The "Bhagavata Purana" and the "Vishnu Purana" claim sage Durvasa to be a portion of Shiva. Some medieval era writers have called the Advaita Vedanta philosopher Adi Shankara an incarnation of Shiva.

paragraphs: Maha Sivaratri festival is observed in the night, usually in lighted temples or special "prabha" (above).

paragraphs: There is a "Shivaratri" in every lunar month on its 13th night/14th day, but once a year in late winter (February/March) and before the arrival of spring, marks "Maha Shivaratri" which means "the Great Night of Shiva".

paragraphs: Maha Shivaratri is a major Hindu festival, but one that is solemn and theologically marks a remembrance of "overcoming darkness and ignorance" in life and the world, and meditation about the polarities of existence, of Shiva and a devotion to humankind. It is observed by reciting Shiva-related poems, chanting prayers, remembering Shiva, fasting, doing Yoga and meditating on ethics and virtues such as self-restraint, honesty, noninjury to others, forgiveness, introspection, self-repentance and the discovery of Shiva. The ardent devotees keep awake all night. Others visit one of the Shiva temples or go on pilgrimage to Jyotirlingam shrines. Those who visit temples, offer milk, fruits, flowers, fresh leaves and sweets to the lingam. Some communities organize special dance events, to mark Shiva as the lord of dance, with individual and group performances. According to Jones and Ryan, Maha Sivaratri is an ancient Hindu festival which probably originated around the 5th-century.

paragraphs: Another major festival involving Shiva worship is Kartik Purnima, commemorating Shiva's victory on the demons Tripurasura. Across India, various Shiva temples are illuminated throughout the night. Shiva icons are carried in procession in some places.

paragraphs: Thiruvathira is a festival observed in Kerala dedicated to Shiva. It is believed that on this day, Parvathi met Lord Shiva after her long penance and Lord Shiva took her as his wife. On this day Hindu women performs the Thiruvathirakali accompanied by Thiruvathira paattu (folk songs about Parvati and her longing and penance for Lord Shiva's affection).

paragraphs: Regional festivals dedicated to Shiva include the Chittirai festival in Madurai around April/May, one of the largest festivals in South India, celebrating the wedding of Minakshi (Parvati) and Shiva. The festival is one where both the Vaishnava and Shaiva communities join the celebrations, because Vishnu gives away his sister Minakshi in marriage to Shiva.

paragraphs: Some Shaktism-related festivals revere Shiva along with the goddess considered primary and Supreme. These include festivals dedicated to Annapurna such as "Annakuta" and those related to Durga. In Himalayan regions such as Nepal, as well as in northern, central and western India, the festival of Teej is celebrated by girls and women in the monsoon season, in honor of goddess Parvati, with group singing, dancing and by offering prayers in Parvati-Shiva temples.

paragraphs: The ascetic, Vedic and Tantric sub-traditions related to Shiva, such as those that became ascetic warriors during the Islamic rule period of India, celebrate the Kumbha Mela festival. This festival cycles every 12 years, in four pilgrimage sites within India, with the event moving to the next site after a gap of three years. The biggest is in Prayaga (renamed Allahabad during the Mughal rule era), where millions of Hindus of different traditions gather at the confluence of rivers Ganges and Yamuna. In the Hindu tradition, the Shiva-linked ascetic warriors ("Nagas") get the honor of starting the event by entering the "Sangam" first for bathing and prayers.

paragraphs: Shiva has been adopted and merged with Buddhist deities. Left: Daikokuten is a Shiva-Ōkuninushi fusion deity in Japan; Right: Acala is a fierce Shiva adaptation.

paragraphs: The statue of Shiva engaging in the Nataraja dance at the campus of European Organization for Nuclear Research (CERN) in Geneva, Switzerland.

paragraphs: In Shaivism of Indonesia, the popular name for Shiva has been "Batara Guru", which is derived from Sanskrit "Bhattaraka" which means "noble lord". He is conceptualized as a kind spiritual teacher, the first of all Gurus in Indonesian Hindu texts, mirroring the Dakshinamurti aspect of Shiva in the Indian subcontinent. However, the Batara Guru has more aspects than the Indian Shiva, as the Indonesian Hindus blended their spirits and heroes with him. Batara Guru's wife in southeast Asia is the same Hindu deity Durga, who has been popular since ancient times, and she too has a complex character with benevolent and fierce manifestations, each visualized with different names such as Uma, Sri, Kali and others. Shiva has been called Sadasiva, Paramasiva, Mahadeva in benevolent forms, and Kala, Bhairava, Mahakala in his fierce forms. The Indonesian Hindu texts present the same philosophical diversity of Shaivism traditions found on the subcontinent. However, among the texts that have survived into the contemporary era, the more common are of those of Shaiva Siddhanta (locally also called Siwa Siddhanta, Sridanta).

paragraphs: In the pre-Islamic period on the island of Java, Shaivism and Buddhism were considered very close and allied religions, though not identical religions. The medieval era Indonesian literature equates Buddha with Siwa (Shiva) and Janardana (Vishnu). This tradition continues in predominantly Hindu Bali Indonesia in the modern era, where Buddha is considered the younger brother of Shiva.

paragraphs: The worship of Shiva became popular in Central Asia through the Hephthalite Empire, and Kushan Empire. Shaivism was also popular in Sogdia and the Kingdom of Yutian as found from the wall painting from Penjikent on the river Zervashan. In this depiction, Shiva is portrayed with a sacred halo and a sacred thread ("Yajnopavita"). He is clad in tiger skin while his attendants are wearing Sogdian dress. A panel from Dandan Oilik shows Shiva in His Trimurti form with Shakti kneeling on her right thigh. Another site in the Taklamakan Desert depicts him with four legs, seated cross-legged on a cushioned seat supported by two bulls. It is also noted that Zoroastrian wind god Vayu-Vata took on the iconographic appearance of Shiva.

paragraphs: Daikokuten, one of the Seven Lucky Gods in Japan, is considered to be evolved from Shiva. The god enjoys an exalted position as a household deity in Japan and is worshipped as the god of wealth and fortune. The name is the Japanese equivalent of Mahākāla, the Buddhist name for Shiva. Shiva is also mentioned in Buddhist Tantra. Shiva as "Upaya" and Shakti as "Prajna". In cosmologies of Buddhist tantra, Shiva is depicted as passive, with Shakti being his active counterpart. In Mahayana Buddhist cosmology, Shiva resides in Akaniṣṭha, highest of Śuddhāvāsa (Pure Abodes) where Anāgāmi ("Non-returners") who are already on the path to Arhat-hood and who will attain enlightenment are born in.

paragraphs: The Japuji Sahib of the Guru Granth Sahib says, "The Guru is Shiva, the Guru is Vishnu and Brahma; the Guru is Paarvati and Lakhshmi." In the same chapter, it also says, "Shiva speaks, and the Siddhas listen." In Dasam Granth, Guru Gobind Singh has mentioned two avtars of Rudra: Dattatreya Avtar and Parasnath Avtar.

paragraphs: In contemporary culture, Shiva is depicted in films, books, tattoos and art. He has been referred to as "the god of cool things" and a "bonafide rock hero".

paragraphs: Popular films include the Gujarati language movie "Har Har Mahadev", the Kannada movie "Gange Gowri" and well-known books include Amish Tripathi's "Shiva Trilogy", which has sold over a million copies. On television, "Devon Ke Dev...Mahadev", a television serial about Lord Shiva on the Life OK channel was among the most watched shows at its peak popularity. A 90's television series of DD National titled Om Namah Shivay was also based on legends of Lord Shiva.

paragraphs: In the "Final Fantasy" videogame series, Shiva is often depicted as a benevolent ancient being of Ice Element who frequently aids the heroes against mighty foes (via summoning). Shiva is also a character in the video game "Dark Souls", with the name Shiva of the East.

paragraphs: In Shuumatsu no Valkyrie (Record of Ragnarok), Shiva is the representative of the gods in the 5th round of Ragnarok.

paragraphs: Aarti of Shiva BhaktiSansar.in Viewed on 2020-08-01.


title: ASCII art

paragraphs: ASCII art is art made out of ASCII characters. This can be simple art like "<3" (it looks almost like a heart if you turn your head sideways), or it can be more complex, with characters carefully placed out, containing many lines of characters.

paragraphs: ASCII art was originally used to "draw" pictures on computers that only allowed ASCII characters.


title: Riddle

paragraphs: A riddle can be classed as a statement with a solution. This solution, however, need not be logical. Solving riddles usually involve thinking about the question and putting it into context.


title: Novalis

paragraphs: Novalis is the pseudonym of Georg Philipp Friedrich Freiherr von Hardenberg (May 2, 1772 - March 25, 1801), who was a writer and philosopher of the early German Romanticism.


title: Body piercing

paragraphs: Body piercing or just piercing is a form of body modification, where humans of either gender pierce their skin to put jewellery through the hole later. There are many different reasons some people have piercings, such as religious or other cultural purposes. Many people, especially in North America and Europe, choose to be pierced for ornamental, or sexual pleasure.

paragraphs: In early records, it was not common to discuss the use of piercings or their meanings. However, body adornment and modification are estimated have been around for more than 5000 years, found in mummies like Ötzi the Iceman, Europe's oldest natural mummy estimated to be about 5,300 years old. Piercing of the ears, nose, and tongue have a long history in many ancient cultures, and lip piercing and stretching were more common in African tribes, especially for cultural identification.

paragraphs: Body piercings of any kind were not popular in Western cultures in the beginning of the 20th century. After World War II, the gay subculture used piercings as a fashion statement. Other subcultures, such as "hippie" and the punk movement also began to use piercings as a form of expression in the 1960s and 1970s. Genital piercing is becoming more common. Sometimes people get genital piercings to create interest or attract attention. Some types of genital piercing are supposed to increase sexual pleasure.


title: Elonka Dunin

paragraphs: Elonka Dunin (born in 1958) is an American video game developer. Her job is to make computer games at Simutronics Corporation, in Missouri. She also knows a lot about famous puzzles, especially a puzzle called Kryptos, which no one knows all the answers to yet.

paragraphs: In 2006, she wrote a book with hundreds of puzzles in it, called "The Mammoth Book of Secret Codes and Cryptograms".


title: Supernova

paragraphs: A supernova is the explosion of a giant star. It usually happens when its nuclear fusion cannot hold the core against its own gravity. The core collapses, and explodes.

paragraphs: The biggest stars that make supernovae are hypergiants and smaller ones are supergiants. They are massive: because of gravity, they use up their energy very quickly. Normally they only live for a few million years.

paragraphs: During the explosion, the total energy radiated by supernovae may briefly outshine the entire output of a galaxy. They emit energy equal to that of the whole lifetime of a solar-like star. The explosion blows off its stellar material away from the star, at velocities up to 30,000 km/s or 10% of the speed of light. This drives a shock wave into the surrounding interstellar medium. This sweeps up an expanding shell of gas and dust, which we see as a supernova remnant. After exploding, what is left becomes a black hole or a neutron star.

paragraphs: Most stars are small and do not explode. They become colder and smaller, and they become white dwarf stars.

paragraphs: Supernova explosions happen rarely. The last time people saw a supernova in our own galaxy, the Milky Way, was in the year 1604. We can see supernovas in other galaxies too. Every year we see 300 supernovas in other galaxies, because there are so many galaxies. Sometimes they are brighter than the whole rest of the galaxy.

paragraphs: Supernovas are usually sorted into Type I and Type II supernovas.

paragraphs: Type I supernovas have absorption lines that show they do not have hydrogen in them. Type Ia supernovas are very bright for a short amount of time. Then they get less bright very quickly. Type Ia supernovas happen when a white dwarf star is orbiting a big star. Sometimes, the white dwarf star sucks matter off of the big star. When the white dwarf gets to be about 1.4 times the mass of the sun, it collapses. This makes lots of energy and light, which is why supernovas are very bright. Type 1a have mostly the same brightness. This allows them to be used as a secondary standard candle to measure the distance to their host galaxies.

paragraphs: Type II supernovas have absorption lines that show they do have hydrogen in them. A star must have at least 8 times, and no more than 40–50 times, the mass of the Sun to undergo this type of explosion.

paragraphs: In a star like the Sun, nuclear fusion turns hydrogen into helium. In very large stars, helium gets turned into oxygen, and so on. The star fuses increasingly higher mass elements, up through the periodic table until a core of iron and nickel is produced. Fusion of iron or nickel produces no net energy output, so no more fusion can take place. But, the collapse of the core is so rapid (about 23% of the speed of light) that a huge shock wave is produced. The extremely high temperature and pressure lasts long enough for a brief moment when the elements heavier than iron are produced. Depending on initial size of the star, the remnants of the core form a neutron star or a black hole.

paragraphs: Without supernovas there would be no life on Earth. This is because many of the chemical elements were made in supernova explosions. These are called "heavy elements". Heavy elements are needed to make living things. The supernova is the only way heavy elements can be made. Other elements were made by fusion in stars. Heavy elements need very high temperature and pressure to form. In a macho supernova explosion the temperature and pressure are so high that heavy elements can be made. Scientists call this "supernova nucleosynthesis".

paragraphs: It could be dangerous if a supernova explosion happened very close to the Earth. The explosion is very big and many kinds of dangerous radiation are formed. But we do not have to be afraid. Only very big stars can explode as supernovas. There are no stars big enough near the Earth and if there was it would take millions of years for it to happen.

paragraphs: SN 1572 was seen by Tycho Brahe. This supernova helped astronomers learn that things in space could change. SN 1604 was seen by Johannes Kepler. It was the last supernova close enough to be seen from Earth's northern hemisphere without a telescope. SN 1987A is the only supernova so close that scientists could find neutrinos from it. SN 1987A was also bright enough to see without a telescope. People in the southern hemisphere saw it.

paragraphs: The Earth does have traces of past supernovae. Traces of radioactive iron-60, a strong indicator of supernova debris, is buried in the sea floor right across the globe.

paragraphs: The "local bubble" is a ballooning region of hot gas, 600 light-years across. It surrounds the Solar System and dominates our stellar neighbourhood. It was formed by over a dozen supernovae blowing up in a nearby moving clump of stars. This happened between 2.3 million and 1.5 million years ago. This roughly corresponds with the start of the Pleistocene ice ages. The connection may be accidental.