The first analog video color format, which uses one channel and a single cable (the audio tracks transmit in separate channels and cables). All old analog TVs and many digital TVs have composite video inputs (see LG example below). Old analog TVs also included S-video inputs, and many also supported the higher-quality component video. See S-video
and component video
Back to the 1950s
Composite video was created when color was added to black & white TV in 1954. Two color signals (U and V) were multiplexed with the original monochrome signal (Y) and transmitted in the same TV channel (see YUV
Composite Video Is Yellow
The yellow RCA jack is the composite video socket found on myriad video devices. However, professional equipment may not support composite video.
Composite Video on Digital TVs
This excerpt from a 2017 LG OLED TV manual shows that even the most modern digital TVs accept analog composite video signals in order to connect to old VCRs and other early video sources.
How YUV Is Separated
This diagram shows the relationship between composite, S-video and component video signals. The device (bottom) shows the actual ports from an NVIDIA graphics card. (Bottom image courtesy of NVIDIA Corporation.)