8-Track tapes were a popular music format in the 1970s, especially for car players. In the most-used configuration, their titular 8 tracks were used to provide 4 stereo programs (taking two tracks each, left and right). A quadraphonic format with four tracks per program was also used. The popularity of this format declined as cassettes improved in audio quality, and it was phased out in the early 1980s. However, after it had faded out as a consumer format, a form known as the Jingle Card Cassette remained in use for years in the radio industry.
An 8-track tape consisted of a 1/4"-wide magnetic tape mounted in a continuous loop around a single reel in a plastic cartridge. The tape moved at 3.75 in. per second, and at the end of a track a piece of conductive foil caused the player to change tracks. The single-reel structure could only move forward, so no rewind feature was possible. Another drawback was the fact that albums at the time were typically designed for vinyl records, which had two sides, and often lacked good break points at the one-quarter and three-quarters marks needed to divide them into the tracks of an 8-track, so sometimes songs were divided between two tracks with a noticeable pause in between, or other rearrangements were done to the album.
There was also some use of 8-track tapes as a data storage medium, as with the original Compucolor computer (though the later and more popular Compucolor II had a disk drive instead).