Tedbot experimented with the Raspberry Pi’s GPIO (General Purpose Input/Output) pins. In his article he describes three methods to do this: Python, Bash and C. Using those three programming languages he turns on and off a LED.
He used an old floppy disk drive IDE ribbon cable to connect the RPi’s GPIO header. Soldered some breadboard-friendly header pins onto the other end.
It would be way better to use an add-on GPIO expansion board, but this does demonstrate the basic use of the RasPi’s GPIO usage.