In electronics, a jack is generally a socket (female) connector, but because the related term jack plug is often abbreviated to just jack, confusion can easily arise. To avoid confusion, the specific terms plug or socket are often preferable. The term jack occurs in several related terms:

• The telephone jack of old-style manual telephone exchanges, which is the socket fitting the original 1/4" jack plug. Also known as a phone jack.
• The RJ in RJ11, RJ45 and similar, which stands for registered jack.
• The RCA jack, also known as a phono jack.
• The EIAJ Plug (or formally EIAJ RC-5320A) with a yellow tip for consumer appliances requiring less than an 18.0 volt power supply.

When used with a size, the term jack refers to the socket that matches the corresponding size of jack plug. For example:

• 6.35mm or 1/4" TRS connector jack
• 3.5mm miniature jack
• 2.5mm subminiature jack

A headphone jack or earphone jack is normally one of the three standard sizes of jack, but the term could refer to any socket used for this purpose.

Jack plugs are used for microphones.

See also

• TRS connector
• Home cinema
• Line level
• Sound card