Multitasking
From TreoCentral
Multitasking refers to the ability of a single CPU to execute operating system instructions for multiple programs at one time. For the user, this means that multiple programs can be open and running simultaneously avoiding the need to close one program before starting another.
Windows Mobile supports true multitasking, but PalmOS does not. With PalmOS, it may appear that multiple programs are running at one time, but in actuality only one is running at any given time.
For more information, see this Wikipedia article.
