The test card usually has a set of line-up patterns, enabling televisions to be adjusted to show the picture correctly. (Compare with SMPTE color bars). They would also typically be broadcast to a background of specially composed music, to avoid having to pay licencing fees for existing compositions. There is now a cult following for test-card music.

The most famous British test card is Test Card F which incorporates a colour photograph, used on the BBC and ITV from the beginning of colour broadcasts in the late 1960s. It was later updated as Test Card J, and for widescreen broadcasts as Test Card W.

Formerly a common sight, test cards are now only rarely seen. Two things have led to the demise of the test card:

• Modern microcontroller-controlled televisions rarely if ever need adjustment, so test cards are much less important than previously.
• The financial imperatives of commercial television broadcasting mean that air-time is now typically filled with programmes and commercials 24 hours a day, and non-commercial broadcasters have to match this.

• Images of test cards
• Trade test transmission