RFID is an Arduino library that offers an API for interfacing with RFID sensors. It supports two communication protocols, UART and Wiegand.
RFID is a way of wireless identification. An RFID reader emits a magnetic field, and then an RFID tag (which doesn’t have its own power) is able to harvest some energy from that field and respond with its stored ID data. Following that, the reader will receive these data and send them to the computing device behind it. RFID tags appear in a number of forms and sizes. They come in the shape of a credit card, or a sticker, and there are even small implantable glass RFID capsules. Though one must take caution when carrying RFID tags. The tags respond to any device that asks for their ID, not just the one someone’s interested in!
RFID abstracts away the process of communicating with an RFID reader. When new data arrive, the library receives them, extracts the available information from the data frame and delivers the results to the user.
There is a tutorial on RFID on codebender’s blog. The source code is available on GitHub.