A microcontroller (
uC) is a computing device. Its main job is to perform computations… it takes some data from its memory, manipulates them, and then stores them back to memory. But having data in a uC’s RAM doesn’t do much good. In order to make use of that information, we have to be able to take it out of the uC and realize it in some way. To do that, a uC has
outputs that can transfer out bits of information to devices that can display it, make sound or light, cause something to move, etc.