let's take the case where a variable is already known (for example, a ship or plane might have a known elevation), then the receiver can determine its position using only three satellites. Sometimes some of the GPS receivers may use additional clues or guesses (such as reusing the last known altitude, inertial navigation, or including information from the vehicle's computer) to provide a degraded position when fewer than four satellites are visible. RFIDRFID is a remote storage and storage method to retrieve data using devices called RFID tags. An RFID tag is a small object, such as an adhesive sticker, that can be attached to or embedded in a product. RFID tags contain antennas that allow them to receive and respond to radio frequency requests from an RFID transceiver. It offers very high security. Each tag is identified by a unique identification number (UIN), which can be programmed at the factory or manually and then password protected. The excellence of this tag is that the data on the chip using sophisticated algorithm techniques cannot be duplicated or manipulated. Therefore making it the perfect tool for secure access