The AK-47 is a selective fire, gas operated 7.62x39mm assault rifle, first developed in the Soviet Union by Mikhail Kalashnikov. The designation AK-47 stands for Kalashnikov automatic rifle, model of 1947 (Russian: Автомат Калашникова 47, tr.Avtomat Kalashnikova 47). It is therefore also known as Avtomat Kalashnikova (or simply 'AK'), Kalashnikov or Russian jargon Kalash).
Design work on the AK began in 1944. In 1946 a version of the rifle, the AK-46, was presented for official military trials, and a year later the fixed stock version was introduced into service with select units of the Red Army. An early development of the design was the AKS-47 (S—Skladnoy or "folding"), which differed in being equipped with an underfolding metal shoulder stock. The AK-47 was officially accepted by the Soviet Armed Forces in 1949 and used by the majority of the member states of the former Warsaw Pact.
The AK-47 fires the 7.62x39mm cartridge which produces significant wounding (including remote wounding effects known as hydrostatic shock) in cases where the bullet tumbles and fragments in tissue, but which produces relatively minor wounds in cases where the bullet exits before beginning to yaw.
The original AK-47 was one of the first true assault rifles. Even after seven decades, due to its durability, low production cost and ease of use, the model and its variants remain the most widely used and popular assault rifles in the world. It has been manufactured in many countries and has seen service with regular armed forces as well as irregular, revolutionary and terrorist organizations worldwide. The AK-47 was also used as a basis for the development of many other types of individual and crew-served firearms. More AK-type rifles have been produced than all other assault rifles combined.