The AK-47, officially known as the Avtomat Kalashnikova (Russian: Автома́т Кала́шникова, lit. 'Kalashnikov's automatic rifle'; also known as the Kalashnikov or just AK), is a gas-operated, 7.62×39mm assault rifle developed in the Soviet Union by Mikhail Kalashnikov in the aftermath of World War II. It is the originating firearm of the Kalashnikov rifle (or "AK") family. The number 47 refers to the year it was finished.

Design work on the AK-47 began in 1945. It was presented for official military trials the following year, and in 1948 the fixed-stock version was introduced into active service with selected units of the Soviet Army. An early development of the design was the AKS (Skladnoy, or 'folding'), which was equipped with an underfolding metal shoulder stock. In early 1949, the AK was officially accepted by the Soviet Armed Forces[9] and used by the majority of the member states of the Warsaw Pact.

Even after more than seven decades, the model and its variants remain the most popular and widely used rifles in the world because of their reliability under harsh conditions, low production cost compared to contemporary Western weapons, availability in virtually every geographic region, and ease of use. The AK has been manufactured in many countries and has seen service with armed forces as well as irregular forces and insurgencies worldwide. The model was the basis for developing many other types of individual, crew-served and specialised firearms. As of 2004, "[o]f the estimated 500 million firearms worldwide, approximately 100 million belong to the Kalashnikov family, three-quarters of which are AK-47s".[4]