An RFID tag is a small electronic device that uses radio waves to transmit data. It typically consists of a microchip and an antenna, allowing it to communicate with an RFID reader. These tags can be passive, active, or semi-passive, depending on their power source and functionality. RFID tags are commonly used for tracking and identifying objects, such as in inventory management, supply chain logistics, and access control systems. They can store various types of information, making them useful in industries like retail, healthcare, and transportation.