An Operating system that is capable of allowing multiple software processes to run at the same time. Below are some examples of multitasking Operating Systems.
Unix Windows 2000 Windows XP Mac OS X
Multitasking operating systems allow more than one program to run at a time. They can support either preemptive multitasking, where the OS doles out time to applications (virtually all modern OSes) or cooperative multitasking, where the OS waits for the program to give back control (Windows 3.x, Mac OS 9 and earlier).