The 21 Pin Scart Socket Explained - What are all those pins for?

The scart connector has been around for many years and is the main connection between most retro games consoles and computers and their television display.  The scart is widely found on european systems - US TVs lacked the socket and had to make do with composite video or internally modify the system for an RGB connection.

The scart is both an input and output connection - providing audio & video connections in both directions depending upon the device.