A TRS connector (tip, ring, and sleeve) also called an audio jack, phone plug, jack plug, stereo plug, mini-jack, or mini-stereo, is a common audio connector. It is cylindrical in shape, typically with three contacts, although sometimes with two (a TS connector) or four (a TRRS connector).
It was invented for use in telephone switchboards in the 19th century and is still widely used, both in its original quarter-inch (6.3 mm) size and in miniaturized versions. The connector's name is an initialize derived from the names of three conducting parts of the plug: Tip, Ring, and Sleeve – hence, TRS.
In the UK, the terms jack plug and jack socket are commonly used for the respectively male and female TRS connectors.
In the U.S., a female connector is called a jack. The terms phone plug and phone jack are commonly used to refer to TRS connectors, but are also sometimes used colloquially to refer to RJ11 and older telephone plugs and the corresponding jacks that connect wired telephones to wall outlets. (The similar terms phonon plug and phonon jack refers to RCA connectors.) To unambiguously refer to the connectors described here, the diameter or other qualifier is often added, e.g. 1/4-inch phone plug", "3.5 mm phone jack, and balanced phone jack or stereo phone plug for the three-contact version.