The AK-47 is a selective-fire, gas-operated 7.62×39mm assault rifle, first developed in the Soviet Union by Mikhail Kalashnikov. It is officially known as Avtomat Kalashnikova. It is also known as a Kalashnikov, an "AK", or, in Russian slang, Kalash. The original AK-47 was one of the first true "assault rifles" to be manufactured, Even after six decades the model and its variants remain the most widely used and popular assault rifles in the world because of its durability, low production cost, and ease of use.