But the cool thing about Raspberry is not its size, but how it was made. The computer is a very simplified system that follows the same Von Neumann architecture that has been used since the 50's and is still very practical for modern computers. It was developed to make the principles of computing in a very simple way to understand, I mean, really simple. You don't need to know anything about computer technology and you can connect the Raspberry Pi in any device that also has a computer and reprogram it to make something, or to make homemade devices that is programmed to make something, use your imagination!
Here it's a photo of this great computer:
Here, for example, it's a usage between raspberry pi and AirPlay:
Anyway, if you want to learn computing in a easy way, and for cheap prices (something like 60 bucks) then, raspberry pi it's the best option!