An RFID tag can be active or passive. Passive tags, which are more economical and widespread, are made up of an aluminium or copper antenna, a memory microchip and a support for the protection of this chip. They do not have a battery and require no maintenance. The passive tags are made to transmit a unique serial code when they receive an appropriate electromagnetic stimulus. The active tags are more sophisticated electronic devices. Provided with an internal battery that powers them and that enables very great transmission distances to be achieved (over 400m in the open for some models), they are equipped with a very complicated electronic system that allows the application to be customized on the basis of individual requirements. These are typically used in warehouses to monitor frequently transported pallets and, when necessary, to keep track of inventory data related to the manufacture history of the commodity or of information concerning the physical and organoleptic characteristics of the stored goods (temperature, humidity etc.).