There are a host of connectors that are used for audio, both consumer and professional. The quarter inch connector, also known as guitar, telephone, phone, TS for tip-sleeve, and TRS for tip-ring-sleeve, was originally used for telephone switchboards, hence the names telephone and smaller version of the telephone connector is called TT, for tiny The most recognizable consumer connector is the RCA, also known as a phono MIDI connector is a 5-pin DIN plug, that was also used on some of the earliest PCs as the keyboard very common digital audio interface connector today, is a DB25 named for the 25 pins. Probably because one connector can interface eight channels, it’s popular on digital audio workstation hardware and control XLR connector now found on almost every microphone was originally called a Cannon X connector, made by the Cannon Electric Company in Los Angeles. When Cannon added a lock so that the cable wouldn’t accidentally fall out, they called it a Cannon XL. They later added a resilient polychloroprene insulation to the female connectors, and changed the name to Cannon XLR.