APS
APS is an abbreviation for Advanced Photo System, which refers to a film photography format that was discontinued in 1996 after its introduction by Kodak and other manufacturers. The 24mm film was contained in a cartridge that could be dropped in, and it was capable of being shot in three distinct formats. It was utilized primarily in compact cameras, but some single-lens reflex cameras also employed it.
Do you have a better definition? Share it in the comments.