Unlocking using RFID tag is a more and more popular way for entering a building or space and unlocking special rooms. RFID tags work as a key and as such are most widely used in access control or opening electronic locks. Its size makes it practical and convenient; it is water proof and very durable. It is usually carried as a key ring or a replacement for RFID card.
Each tag has own unique serial number within its contactless chip.
We can say that the forerunner of modern RFID devices is a covert listening device more popularly known as a bug or wire that sends signals over radio waves. Modern RFID tags operate at frequencies of 125 KHz and 13.56 MHz.
