An RFID card (Radio Frequency Identification card) is a small card embedded with a chip and antenna that allows for wireless communication. It uses radio waves to transmit data to a reader, enabling quick identification and access control. RFID cards are commonly used in various applications, such as security systems, public transportation, and inventory management. These cards can be passive, active, or semi-passive. Passive RFID cards do not have a battery and rely on the reader's signal for power, while active RFID cards have their own power source. The technology offers convenience and efficiency, making it a popular choice for businesses and organizations.