RFID Identificators may be grouped according to various criteria:
1. According to shape:
- Card (ISO 7816-1), size 86 x 54 x 0.76 mm;
- Clamshell card, size 86 x 54 x 1.8 mm;
- Keyring – different shapes and sizes;
- Glass capsule, implanted in animals;
- Animal ear mark;
- Nail and etc.
2. According to power supply:
- Passive tags – tags without an on-board power source (battery). The simple design of these tags makes them very durable – they have a service life of about ten years, and resistant to external conditions (temperature, humidity, chemicals, etc.). Their price is very affordable compared to the other types of identificators. One drawback is the distance for reading.
- Active tags – tags with an on-board power source. This allows a greater reading distance, an option to incorporate a chip and the performance of additional functions: temperature measurement, monitoring of set parameters, etc.
- Battery-assisted passive tags with an on-board power source like in the active tags. The battery improves the reading distance. Some of these tags are not activated until alerted by the reader, thus saving the battery life.
3. According to the possibility for reading and writing:
- Read-only – tags having a factory-assigned serial number which may not be changed. Read-only tags are very common on account of their cheap price and ease of use.
- Write Once Read Many (WORM) – the writing is done at the first use of the identificator. WORM tags have a good price/productivity ratio and are widely used in business applications.
- Read Write (RW) tags where data can be written and re-written many times (from 10 to 100,000 and even more). When active RW tags are used, the writing can be done by both the reader and also by the tag itself. RW tags may be used in many different applications but their high price (for the time being) makes them less affordable.