How does the payment terminal work in stores?

Question

Fintech

What is the procedure for checking and withdrawing money?
1) Getting a client ID (if you can call it that), connecting to the Internet, checking against the database for availability of funds, withdrawing
2) Is the terminal connected to a computer, and all communication between the server and the terminal takes place on the computer?

Answer 1

The terminal only needs power, it seems to be knocking from it like via GPRS to the server of its bank, and then everything is already clear.