Do you remember how we compared the human body to robots in Chapter 1, The World around Us? Microcontrollers are like the brains in human beings. Similar to human brains, microcontrollers work on a simple input-output concept. So, what is this input-to-output concept?

Anything that is taken in or put in a system is called an input; similarly, output is what is given out of the system.

Look at the following diagram-it shows what a system looks like. This system could be a microcontroller or a human brain:

Microcontrollers receive the input information; they process that information and then produce an output. The human brain processes a lot of information too, even before birth. All day, every day, it processes information such as sounds, images, visuals, smells, touch, pain, expressions, and so on. What do you think is the input to the brain? The sense organs in humans provide this input to the brain.