GPIO stands for General-Purpose Input/Output. It refers to programmable pins found on microcontrollers, single-board computers (like Raspberry Pi), and other hardware platforms. These pins can be configured by software to act as either input (to read signals from sensors or switches) or output (to control devices like LEDs, relays, or motors). GPIOs enable direct hardware interfacing, making them essential for embedded systems, IoT projects, and prototyping. While not a cybersecurity concept per se, GPIOs can be relevant in security contexts, such as hardware hacking, physical security controls, or when securing IoT devices against unauthorized access to physical interfaces.