Raspberry Pi – GPIO
GPIO is an abbreviation for „General Purpose Input Output“. Many processor pins of the Raspberry Pi chip are attached to the 40-Pin Header of the Raspberry. A GPIO can be seen as an interface between the processor chip and the rest of the world. This pins can be used as output or input. The behaviour is programmable by software. If you use a GPIO as output you can e.g. switch on/off a LED or motor. Used as input the pin can be used to query a push-button or to read the signal of a photo sensor.