Perhaps you should start reading this:

https://en.wikipedia.org/wiki/Radio-frequency_identification

Further reads depend on the RFID system of your choice. Just 1 example:

https://playground.arduino.cc/Learning/MFRC522

RFID has two components , the rf tag and the rf tag reader. The communication between the two components is through the rf waves. The reader is able to instruct the tag to read and send its id information to the reader where it will be decoded and displayed.

For the vendors of the RFID products in India please refer to the link: https://dir.indiamart.com/impcat/rfid-tag.html?biz=10

You can choose the devices with the specifications and prices suitable to you.

You can use biometrics also for the identification by loading them in the TAGs

You can also connect the reader to a microelectronic to control the whole system because the reader has a micro controller.

Best wishes

Thank you Mr. U. Dreher and Mr. Abdelhalim Zekry for your valuable answers.

Do we need any software to write information on the tag?

You'll certainly need some kind of software (at least some serial terminal software). But this depends on the specific RFID reader/writer.

Thank you so much.