RFID systems are becoming more and more prevalent. We drive through tolls and the RFID tag in our car is automatically read and we are charged. Tags are included on items in stores to deter shoplifting. Hospital equipment is tagged so that supplies can be tracked. And, of course, infrastructure products are being tagged at manufacture so that critical QC/QA information can be tracked throughout the product's life cycle. They are everywhere but... how does it actually work?