Keep in mind the RFID is used to identify objects or people. Its advantages are that it requires no human intervention, tags can usually be read even when a tag is not facing a reader antenna (tags can't be read through metal and some other materials), and the information can be transmitted to computers in real time. Typically, when a read reads a tag, it passes three things to a host computer system: the tag ID, the reader's own ID and the time the tag was read. By knowing which readers are in which locations, companies can know where a product is, as well as what it is, and because of the time stamp, they can know everywhere it's been.