Active Tags: RFID tags that use an embedded battery to provide power and a radio signal. These generally cost between $10 and $100. They are much more expensive than passive tags, but possess greater data capacity and range.

AutoID Center: the private/academic consortium associated with the Massachusetts Institute of Technology (MIT) that invented the concept of the electronic product code (EPC). Many major global retailers and manufacturers were members before this group became EPCGlobal.

Antenna: structures that radiate and receive radio energy. These are built into both RFID readers and tags.

Class 0: the current EPC standard for factory-programmed tags. These tags come from the factory with a preset number which cannot be changed. Class 0 is based on protocols initially invented by Matrics, Inc.

Class 0+: a non-standard extension to Class 0 that allows tags to be programmed with new data.

Class 1: the current EPC standard for write-once tags. These tags are designed to be written with data once at the time the tag is applied to an object, quite often in a printer when a "smart label" is printed to apply to a box.

EPC or Electronic Product Code: a unique number that identifies an item in the supply chain. It's designed to be stored in an RFID chip to allow an item to be tracked as it moves throughout the supply chain. You can think of it as a universal product code (UPC) plus a serial number, with some differences.

EPCglobal: the non-profit organization that manages standards and numbering schemes associated with EPC and the successor organization to the Auto ID Center. EPCglobal is a membership-driven organization and is a subsidiary of the Uniform Code Council and EAN International, the leading retail bar code standards organizations best known for UPC.

Frequency: the speed that a radio signal cycles through its minimum and maximum values during a given time period. RFID tags operate at different frequencies. EPC operates in frequency bands around 868 MHz (Europe) or 915 MHz (United States).

Interference: anything that prevents radio waves from traveling between a tag and reader correctly and causes the tag to be read incorrectly. Interference is sometimes caused by other radio signals or by some physical objects - metals and liquids- that absorb or reflect the radio signals.

ONS - Object Name Service: an element of the overall EPC system that allows an EPC number in a tag to be translated into a location on the web where information about that object is stored.

Orientation: whether or not a tag is aligned with the reader. Read ranges are generally longer when this is the case.

Passive Tags: RFID tags without batteries. These tags get energy directly from the radio waves transmitted by a reader. They tend to be very inexpensive (less than 50 cents), hold limited data (typically less than 256 bits) and have a shorter read range

than active tags. EPC is focused on passive tags.

Programming: the act of writing data to an RFID tag.

Protocol: a standard way of talking (or communicating) between a reader and a tag. At present, EPC has defined two main protocols - Class 0 and Class 1, the "language" that tags and readers use to talk to each other.

Protocol Speed: the speed at which tags and readers can speak to each other. Varies by protocol, but are typically hundreds of tags per second.

Read-Only Tag: a tag with data that is programmed at the factory and cannot be changed. Class 0 is a read-only tag.

Read Range: the distance where a tag is read by a reader without any objects between the two. This distance varies depending on the reader and tag used, but can be up to 20 feet with the best performing EPC readers and tags.

Reader/Writer: a device designed to read data from or read data to an RFID tag.

RFID - Radio Frequency Identification: a technology that uses radio waves to uniquely identify tagged items.

RFID Chip: the small computer, almost as small as a grain of sand, which is the heart of every RFID tag. The two main parts of an RFID tag are the chip and the antenna.

Smart Label: printed labels that include an RFID tag built into the label.

Tag: an RFID chip packaged so that it can be applied to an item to allow it to be tracked.

Transponder: this is the technical name for a tag.

UHF or Ultra High Frequency: a technical name for a range of frequencies between approximately 400 MHz and 900 MHz. EPC UHF tags operate in the UHF band at around either 868 MHz or 915 MHz.

UHF Generation 2: the next-generation EPC standard currently under development.

Write Once Read Many (W.O.R.M) Tag: a tag that is designed to be written or programmed once and only once and then read many times throughout its life - when it is applied to an object.

Writeable Tag: a tag where data can be written and rewritten many times.

Write Range: the distance where a tag is written by a reader/writer without any object between the tag and the reader/writer. Normally, write range is lower than read range.