The UART (Universal Asynchronous Receiver-Transmitter) protocol is a hardware communication standard that facilitates serial communication between devices. It uses asynchronous transmission, meaning it does not require a clock signal to synchronize data between sender and receiver. UART is commonly used for short-distance communication in embedded systems, microcontrollers, and computers, providing a simple interface for transmitting data over a single wire (TX) and receiving data on another (RX). It is widely utilized in applications like GPS modules, Bluetooth devices, and serial console communication. UART is favored for its simplicity, low cost, and ease of implementation.