An RFID Tag is a small device for storing and transmitting information. It consists of a microchip and an antenna with which it transmits and receives information. There are RFID tags that have a built-in power source (active RFID tags), but the majority of the tags used today do not have a built-in power source (passive RFID tags).

A unique number and/or a certain amount of user memory is stored in the memory of the tag. When a tag enters the reading zone, this information is received by the RFID reader - a device capable of reading and writing information from the RFID tags, and transmitting to the computer or phone for further processing.

RFID Tags can be of various types, depending on the field of application and objectives of the enterprise: from small flexible tags that mark individual products to packaged plastic tags for marking metal containers. Tags may differ in size, shape, materials from which they are made, the method of attachment, memory size, operating frequency, reading range.

The RFID reader contains in its composition a transmitter and an antenna, through which the electromagnetic field of a certain frequency is radiated. The radiofrequency identification tags that fall within the range of the reading field "respond" with their own signal containing useful information (for example, product UPC code). The signal is captured by the reader antenna, the information is decoded and transmitted to the computer or phone for further processing.