The M134 Minigun is a 7.62×51mm NATO, six-barrel rotary machine gun with a high rate of fire (2,000 to 6,000 rounds per minute) which can also fire at a high-sustained rate. It features Gatling-style rotating barrels with an external power source, normally an electric motor. The "Mini" in the name is in comparison to larger caliber designs that use a rotary barrel design, such as General Electric's earlier 20-millimeter M61 Vulcan, and "gun" for the use of rifle caliber bullets instead of shells used by an autocannon.
The Minigun is used by several branches of the U.S. military. Versions are designated M134 and XM196 by the United States Army, and GAU-2/A and GAU-17/A by the U.S. Air Force and U.S. Navy.
"Minigun" refers to a specific model of weapon that General Electric originally produced, but the term "minigun" has popularly come to refer to any externally powered rotary-style gun of rifle caliber. The term is sometimes used loosely to refer to guns of similar rates of fire and configuration regardless of power source and caliber.