What is this TRS bit? Turtle Rock Studios? Transmission Raman Spectroscopy? Not quite, more like Tip-Ring-Sleeve. 

This nifty, gold-plated connector is known by many names, phone plug, phone jack, headphone jack, jack plug, etc. Used to transmit stereo audio signals, these connectors are a mainstay in audio equipment, especially speakers and microphones. For audio, tip is left channel, and ring is right channel, and the sleeve is ground.

Each jack comes with a slim, gold-plated body with three contacts to solder to and a panel mounting hex-nut.

TRS jack connectors don't have to be used only for audio! They make great general-purpose connectors where you need 2 or 3 signals and cheap, common cables. For example, in accessibility tech, these are often used to connect buttons or low voltage actuators.