RFID is a technology that uses radio waves to automatically identify objects. It consists of small chip attached to antennas that can receive and respond to radio frequency queries from a transceiver. There are two main types - passive RFID, which has no internal power supply, and active RFID, which has an internal power supply. RFID is commonly used in supply chains for inventory management and tracking due to its information storage capabilities and ability to reduce errors. Some concerns about RFID include privacy and security if the chips were implanted in humans.