Stands for "General Purpose Input/Output." GPIO is a type of pin found on an integrated circuit that does not have a specific function. While most pins have a dedicated purpose, such as sending a signal to a certain component, the function of a GPIO pin is customizable and can be controlled by software.
Not all chips have GPIO pins, but they are commonly found on multifunction chips, such as those used in power managers and audio/video cards. They are also used by system-on-chip (SOC) circuits, which include a processor, memory, and external interfaces all on a single chip. GPIO pins allow these chips to be configured for different purposes and work with several types of components.
A popular device that makes use of GPIO pins is the Raspberry Pi, a single-board computer designed for hobbyists and educational purposes. It includes a row of GPIO pins along the edge of the board that provide the interface between the Raspberry Pi and other components. These pins act as switches that output 3.3 volts when set to HIGH and no voltage when set to LOW. You can connect a device to specific GPIO pins and control it with a software program. For example, you can wire an LED to a GPIO and a ground pin on a Raspberry Pi. If a software program tells the GPIO pin to turn on, the LED will light up.
Most computer users will not encounter GPIO pins and do not need to worry about configuring them. However, if you are a hobbyist or computer programmer, it can be helpful to learn what chips have GPIO pins and how to make use of them.