Minijack

A minijack is a small analog audio connector, most commonly the 3.5 mm headphone jack, also called the stereo mini-jack. The plug is cylindrical and has a ground sleeve plus one or more signal contacts (tip, ring).

The 3.5 mm connector became widely used in portable electronics from the 1980s onward because of its compact size and broad compatibility with earlier, larger jacks. It remains common on smartphones, laptops, portable players, and gaming consoles, though some devices have begun replacing it with digital ports.

Most plugs are TRS (tip–ring–sleeve) for stereo audio, with tip representing left, ring representing right, and sleeve ground. A four-conductor variant, TRRS, adds a microphone or other control signal, enabling headsets and hands-free devices. Two common pinouts exist: CTIA and OMTP.

Variants include mono TS (tip–sleeve) for unbalanced mono audio, and TRRS for headset signals. The 3.5 mm size uses various mechanical grades and plating; some jacks are reinforced or come in locking styles, and there are combo jacks that share audio and microphone contacts.

Compatibility and adapters: Differences between CTIA and OMTP can affect microphone wiring; adapters or cables with the correct wiring are often required for compatibility. There are adapters to convert 3.5 mm to larger 6.35 mm jacks for professional gear, and to USB‑C or Lightning digital audio where the minijack is removed. In recent years some manufacturers have reduced its use in favor of digital ports.