Origin of RFID
First RFID applications were used in the end of the Second World War. A radar served for the friend enemy recognition. Until today the military use these systems.
The RFID-Technology was developed further for other purposes.
In the industry and the consumer-part RFID is significant for a lot of applications. For example: electronic ski passports, theft and entrance control systems, tank-cards etc.
Passiv tags and aktiv transponders
The passive tags don't need own energy. They are supplied by the radio signal. Aktive transponder have an integrated battery.
There are recordable and only readable variants of both. The memory capacity of the passive tags is about 10 to 100 Byte. They are used to identify a product.
Recordable transponder have a memory capacity of up to several kBit. Sometimes there are microcontroller-function integrated. They are used in Anti-collision systems, patient identification systems in hospitals etc.