Jack (connector)

In electronics, a jack is a socket. In some cases it is arbitrary which of a pair of mating connectors is the plug, and which the socket (see plug). The term jack occurs in several related terms:

• In 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, stands for registered jack. See RJ-XX.

• In the name RCA jack, also known as a phono jack or 1/4" phono jack.

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

• 6.5mm jack
• 1/4" 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.

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