RFID Class-1 Generation-2 (“Gen-2”) tags are used for item level identification in retail environments. “Class-1” refers to the functionality of the tag while “Gen-2” refers to the physcial and logical standards of tag and the encompassing system. These standards are maintained by EPCglobal. “Gen-2” standards were adopted in December of 2004 and offer many advantages over “Gen-1” such as: – An interoperable, global standard – Faster and more flexible read speeds – Faster, more accurate performance through the use of advanced anticollision protocols – An easier way to deploy many readers at one time to end users – Enhanced sercuirty and privacy   

RFID tags are classified as Class 0 through Class 5, depending on their functionality:

Class 0 UHFl read-only, preprogrammed passive tag
Class 1 UHF or HF; write once, read many (WORM)
Class 2 Passive read-write tags that can be written to at any point in the supply chain
Class 3 Read-write with onboard sensors capable of recording parameters like temperature, pressure, and motion; can be semipassive or active
Class 4 Read-write active tags with integrated transmitters; can communicate with other tags and readers
Class 5 Similar to Class 4 tags but with additional functionality; can provide power to other tags and communicate with devices other than readers
(Class-1 Gen-2 RFID tags are backward-compatible with Gen-1 Class-0 and Class 1 tags.)   The full Gen-2 EPCglobal specification is available here.