TRS Cables

TRS is an acronym for 'Tip', 'Ring', 'Sleeve'. In effect, a TRS connector has two black insulation rings on the connector, enabling it to carry three separate signals. A TRS cable therefore contains two cores plus a ground wire. A TRS cable can also be referred to as a 'Stereo Cable', due to its ability to carry two audio signals plus ground. TRS cables are generally made using 'microphone cable', being the common name for two core, twisted pair cable with an outer shield.

Used to Transfer Balanced Line Level Signals
A TRS cable is often used between mixers, power amplifiers and rack effect units where balanced line level cables are required. This cable can also be used as a stereo cable, for stereo signals such as that coming out of a 'headphone' socket.

Two Sizes of TRS Connector
A TRS connector also comes in two different sizes; 1/4" (or 6.5mm) and 1/8" (or 3.5mm). They are both capable of carrying two audio signals plus  ground, the only difference being the physical size of the connector.

Wondering why a TRS cable can carry Balanced or Stereo signal?