The most popular kind of automatic transmission makes use of a torque converter, planetary gears, and hydraulic controls. Continuously variable transmissions (CVT), automated manual transmissions (AMT), and dual-clutch transmissions are further varieties of automatic transmissions (DCT). The terms electronically controlled transmission (ECT), electronic automatic transaxle, and electronic automatic transmission (EAT) are also used interchangeably (EATX).

Another common name for a hydraulic automatic transmission is a “slushbox,” although the phrase “torque converter” can also be used, even though torque converters are also utilized on CVTs.

Many people believe that the 1904 Sturtevant “horseless carriage gearbox” was the first real automatic transmission.

[1][2] The General Motors Hydramatic four-speed hydraulic automatic, which was originally presented in 1939 and uses a fluid coupling rather than a torque converter, is the first mass-produced automatic transmission.