After over a half century of development, radio-frequency identification (RFID) is beginning to move into mainstream applications for automatic identification. RFID is widely seen today as one of the key enabling technologies of the "Internet of Things". However, many challenges still need to be addressed before we can fully benefit from this nascent and ubiquitous technology. In this paper, we present the state of the art of RFID technology and discuss the challenges and open issues in developing next generation RFID applications. © 2009 Springer Science+Business Media, LLC.