This document provides an introduction to RFID technology. It describes how RFID works using radio frequency waves to transfer data between a tag and reader without physical contact. The main components of an RFID system are tags, which can be active with a battery or passive without, and readers that detect tags within a certain range. Common applications discussed include tracking people in hospitals and prisons, locating products in stores, and managing large document collections. Advantages include easy tag installation, large tag memory capacity, and security from replication; disadvantages are difficulty reading tags in liquids/metals and potential privacy issues.