RFID
Radio-frequency identification (RFID) is a technology that was invented in the 1940´s. It uses radio-waves to identify tags containing small amounts of data on a short range (5-20cm). RFID has many standards and is implemented in many ways. Tracking, ticket systems(the Oystercard in London), small payment-cards/services(Japan), badges etc. The tags come in a vide range, but is normally cheap, small and fragile. The readers are also small, meaning it is possible to integrate them in different objects/products.
