Recently, I’ve discovered that which is known as Arduino. Basically, it is an open source, open hardware microcontroller. They give you the software and the hardware plans online and you can build your own. Of course, you can always buy a premade kit (which is my preference).
So… what does this “microcontroller” do? Basically it controls simple input and output on a low level. You want to make something turn on and off a light? A microcontroller can do. Sure, you can do that with your computer too, but an Arduino Uno only costs $30 and takes very little power to run.