[MTMilitiaman]

The original AK-47 was designed by a Russian tank engineer who was tired of seeing his countrymen die and decided to design a better rifle. He was told to design it around the Russian M43 cartridge, known as the 7.62x39. The rifle he created was adopted by the Soviet army in 1947. His name was Kalashnikov. His name is the "K" in AK-47, which roughly translated means "Automatic Kalashnikov Model 1947."
The rifle has undergone several manufacturing changes and in 1974 got another cartridge, the 5.45x39. During the Cold War, the Soviets practically gave the rifle away and it is now believed to be the most prolific in history. Tens of millions were manufactured by the USSR as well as countries like China, Yugoslavia, Bulgaria, Romania, Poland, and Egypt.

It isn't technically correct to call the civilianized versions AKs since they lack the "happy switch" and thus are not capable of automatic fire--eliminating the "A," it is probably more correct to call them Kalashnikovs or AK clones. When people refer to them as AKs here, it is commonly believed that readers known the differences between the semi-auto clones and the full-auto counterparts.