Headphone and earphone jacks on a wide range of equipment. 6.35mm (1/4 in) plugs are common on home and professional component equipment, while 3.5mm plugs are nearly universal for portable audio equipment. 2.5mm plugs are not as common, but are used on communication equipment such as cordless phones, mobile phones, and two-way radios.
Consumer electronics devices such as digital cameras, camcorders, and portable DVD players use 3.5mm connectors for composite video and audio output. Typically, a TRS connection is used for mono unbalanced audio plus video, and a TRRS connection for stereo unbalanced audio plus video. Cables designed for this use are often terminated with RCA connectors on the other end.
Hands-free sets and headsets often use 3.5mm or 2.5mm connectors. Phone connectors are used for mono audio out and an unbalanced microphone (with a shared ground). Four-conductor TRRS phone connectors are used to add an additional audio channel such as microphone input added to stereo output.
Microphone inputs on tape and cassette recorders, sometimes with remote control switching on the ring, on early, monaural cassette recorders mostly a dual-pin version consisting of a 3.5mm TS for the microphone and a 2.5mm TS for remote control which switches the recorder's power supply.
Patching points (insert points) on a wide range of equipment.
Personal computers, sometimes using a sound card plugged into the computer.
The most common arrangement remains to have the male plug on the cable and the female socket mounted in a piece of equipment: the original intention of the design