What is multitasking?
Multitasking is a word that started in the computer industry, and has since passed into common usage. It means, simply, doing several things seemingly at once.Whether you are a processor or a real person, the key word above is seemingly. In practice you (or a CPU) can only do one thing at a time, but if you switch between activities frequently enough, you may give the impression of doing several things simultaneously.
Multitasking is important in controller applications because all but the very simplest controllers need to be able to take care of many things at once. An example would be controlling the temperature of a tank while filling it up (and watching the level) and at the same time watching out for user input from say a push button.
In controllers, as in general computing, there are many ways to arrange for the program to switch between different tasks rapidly. Generally this task management is delegated to an Operating System (O/S). There are may kinds of O/S. You can read about them in a easy to digest paper here.
So, when you select a controller to be a vital component in your product, be sure it comes with a multitasking system that is powerful enough for your needs and easy to use and understand.