MultiFinder was the name of a piece of extension software for the Macintosh available in System 6.0.x. (It, however, had been on board the Macintosh system since System 4.2.) It added the ability to co-operative multitasking|co-operatively multitask between several applications at once, a big improvement over the system without MultiFinder, which could only run one application at a time. With the advent of System 7, MultiFinder became a standard integrated part of the operating system.