There are two basic types of multitasking: preemptive and cooperative.
preemptive – preemptive multitasking, the operating system parcels out CPU time slices to each program (introduced with Mac OS X 10.0)
cooperative multitasking – each program can control the CPU for as long as it needs it. (Previous operating systems (Mac OS 9))
OS/2, Windows 95, Windows NT, the Amiga operating system and UNIX use preemptive multitasking, whereas Microsoft Windows 3.x and the MultiFinder (for Macintosh computers) used cooperative multitasking.