8-track tape (formally Stereo 8: commonly known as the eight-track cartridge, eight-track tape, or simply eight-track) is a magnetic tape sound recording technology popular in the United States from the mid-1960s to the late 1970s when the Compact Cassette format took over. The format is regarded as an obsolete technology, and was relatively unknown outside the United States, the United Kingdom, Canada and Australia.
Stereo 8 was created in 1964 by a consortium led by Bill Lear of Lear Jet Corporation, along with Ampex, Ford Motor Company, General Motors, Motorola, and RCA Victor Records (RCA). It was a further development of the similar Stereo-Pak four-track cartridge created by Earl "Madman" Muntz. A later quadraphonic version of the format was announced by RCA in April 1970 and first known as Quad-8, then later changed to just Q8.