What is "embedded"?

In looking at a computer, some systems are called "embedded". Looking at the hardware, some of them (like ATM's) could be a normal desktop system (though not in a standard case), and run Windows.

So, what makes an "embedded" system? It's the fact that the system is dedicated (or even specifically designed) to run a specific application. The ATM hardware is dedicated to running the ATM application. Or it could be a dedicated control board, like an Arduino.

It's not something that you can write a termpaper on, then fire up the latest FPS. It's a computer that is designed to do only 1 (or a limited number of) specific tasks, and they cannot be changed by the end user.