Decapitation or beheading is the total separation of the head from the body. Such an injury is invariably fatal to humans and most other animals, since it deprives the brain of oxygenated blood, while all other organs are deprived of the involuntary functions that are needed for the body to function. The term beheading refers to the act of deliberately decapitating a person, either as a means of murder or as an execution; it may be performed with an axe, sword, knife, machete or by mechanical means such as a guillotine or chainsaw. An executioner who carries out executions by beheading is sometimes called a headsman. Accidental decapitation can be the result of an explosion, a car or industrial accident, improperly administered execution by hanging or other violent injury. Suicide by decapitation is rare but not unknown. The national laws of Saudi Arabia, Yemen, and Qatar permit beheading; however, in practice, Saudi Arabia is the only country that continues to behead its offenders regularly as a punishment for capital crime.Less commonly, decapitation can also refer to the removal of the head from a body that is already dead. This might be done to take the head as a trophy, for public display, to make the deceased more difficult to identify, for cryonics, or for other, more esoteric reasons. Etymology
The word decapitation has its roots in the Late Latin word decapitare. The meaning of the word decapitare can be discerned from its morphemes de- (down, from) + capit- (head).
The sword was expected to be used upon the slightest sign that the practitioner might yield to pain and cry out—avoiding dishonor to him and to all partaking in the privilege of observing an honorable demise. As skill was involved, only the most trusted warrior was honored by taking part. In the late Sengoku period, decapitation was performed as soon as the person chosen to carry out seppuku had made the slightest wound to his abdomen. Decapitation (without seppuku) was also considered a very severe and degrading form of punishment. One of the most brutal decapitations was that of Sugitani Zenjubō (杉谷善住坊), who attempted to assassinate Oda Nobunaga, a prominent daimyō, in 1570. After being caught, Zenjubō was buried alive in the ground with only his head out, and the head was slowly sawn off with a bamboo saw by passers-by for several days (punishment by sawing; nokogiribiki (鋸挽き). These unusual punishments were abolished in the early Meiji era. A similar scene is described in the last page of James Clavells book Shōgun. Korea
Historically, decapitation had been the most common method of execution in Korea, until it was replaced by hanging in 1896. Professional executioners were called mangnani (망나니) and they were volunteered from death-rows. Pakistan
Pakistans government employs death by hanging for capital punishment. Since 2007, militants from Tehrek-e-Taliban Pakistan have used beheadings as a form of punishment for opponents, criminals and spies in the north west region of Pakistan.