Phono jack

RCA connector

RCA plugs for composite video (yellow) and stereo audio (white and red)
Type	RF coaxial connector
Designer	Unknown, but its name is from Radio Corporation of America
Designed	Early 1940s
Diameter	0.354 in (0.90 cm) (outer, typical)
Cable	Coaxial
Passband	Typically 0-100 MHz

An RCA connector, sometimes called a phono connector or (in other languages) Cinch connector, is a type of electrical connector commonly used to carry audio and video signals. The name RCA derives from the Radio Corporation of America, which introduced the design by the early 1940s for internal connection of the pickup to the chassis in home radio-phonograph consoles. It was originally a low-cost, simple design, intended only for mating and disconnection when servicing the console. Refinement came with later designs, although they remained compatible.

RCA connectors began to replace the older quarter-inch phone connectors for many other applications in the consumer audio world when component high-fidelity systems started becoming popular in the 1950s. However, quarter-inch phone connectors are still common in professional audio, while miniature phone connectors (3.5 mm) predominated in personal stereo systems.

The connection's plug is called an RCA plug or phono plug, for "phonograph." The name "phono plug" is sometimes confused with a "phone plug" which may refer to a quarter-inch "phone plug" – Tip/Sleeve (TS) or Tip/Ring/Sleeve (TRS) connector – or to a 4P4C connector used for a telephone (which is often, though incorrectly, called "RJ9", "RJ10", or "RJ22").

In the most normal use, cables have a standard plug on each end, consisting of a central male connector, surrounded by a ring. The ring is often segmented to provide spring gripping pressure when mated. Devices mount the socket (female jack), consisting of a central hole with a ring of metal around it. The ring is slightly larger in diameter and longer than the ring on the plug, allowing the plug's ring to fit tightly over it. The jack has a small area between the outer and inner rings which is filled with an insulator, typically plastic (very early versions, or those made for use as RF connectors, used ceramic).

The connector was initially used for audio signals. As with many other connectors, the RCA has been adopted for other uses than originally intended, including as a DC power connector, an RF connector, and as a connector for loudspeaker cables. Its use as a connector for composite video signals is extremely common, but provides poor impedance matching. RCA connectors and cable are also commonly used to carry S/PDIF-formatted digital audio, with plugs colored orange to differentiate them from other typical connections.