I often hear about "check", but what is it, where does it come from and how to use it?

Checks are payment vouchers of banks, including cash checks and transfer checks.

Cash check is used to withdraw cash, the company fills in the cash check, and the bank pays after checking it correctly.

The transfer check is paid by inter-unit transfer, without cash. The company fills in the transfer check and sends it to the bank. The bank will transfer the money to the payee's bank account after checking it correctly.