RFID is an automatic identification system. An RFID tag transmits identification or location information, or specifics about the item tagged (i.e. price, colour, date of purchase).
 
As the technology is refined, more pervasive - and invasive - uses for RFID tags are in the works.
 
They are used in some travel cards, there are plans to put them on EURO banknotes and a Singaporean Hospital used them to track patients during the SARs scare. On the high street, stores and manufacturers have put them into everyday products.
 
In the UK, Marks & Spencer, Gillette and Tesco's have come under criticism for using RFID technology.
 
Liberty has joined USA groups to recommend a framework of Fair Information Practices for data collected by the technology. We recommend that the tags be used on packaging only and not the product itself, and that the tags be de-activated once the consumer has left the store.