A RFID Card or tag is a small radio device that is also referred to as a smart label or smart tag, or radio barcode. The tag encompasses of a normal microchip of silicon attached to a small aerial and mounted on a substrate. This tag can then be encapsulated in diverse materials depending upon the usage. The completed or finished tag can be attached to a box, card or any such items and read distantly to determine its identity, state or position. Generally, the RFID tags are mostly used for storing an ID called EPC, Electronic Product Code and identification of physical objects.
The RFID tags can be of different types like read only, read-write, or write once, read many. You can add data or information to the tag or rewrite over existing data or information with the read-write RFID card or tags. Such read-write tags generally have a sequential number that can't be overwritten. Also, using additional storage can be used to store additional data about the items or objects the tag is attached to. Read only tags have data or information stored on them during the manufacturing process. The data or information once stored can never be changed on read only tags. The write once, read many tags have a sequential number written to them once, and that data or information cannot be overwritten later.
The storage capacity depends on the application or the type and manufacture of RFID cards or tags. In other words, the amount of data that can be stored on a single RFID card or tag completely depends on the type of tag. Generally, the storage capacity of RFID card or tag is up to 2 kilobytes. Most RFID card or tags used for industrial applications are prepared with such 2 kb storage capacity, sufficient to store a variety of different item information.
Whereas, simple RFID card or tags that are just applied as IDs carry only 96-bit or 128-bit serial number known as UID, Unique Permanent Identification. The simple tags are cheaper to manufacture, and hence more useful in areas where it can be disposed off with packaging or after one time use. Some manufacturers provide high memory RFID cards or tags that have memory ranging from 4 kb up to 8 kb. Also, military RFID cards or tags have storage memory up to 128 kb.