1. Reason: For a bank deposit account in an enterprise, the debit indicates an increase and the credit indicates a decrease, which is a general lending rule for enterprise asset accounts. However, for banks, it is just the opposite. As can be seen from the bank statement, the borrower registers the enterprise to pay in the current month, and the lender registers the payment, which is just the opposite to the direction of enterprise borrowing.

2. Origin: The reason for this phenomenon can be traced back to the origin of the debit and credit bookkeeping method, which originated in Italy in 12 1 1 year. At that time, the boss of the bank opened two accounts for creditors and debtors, namely accounts receivable and accounts payable. Later, this method spread to Genoa and was improved by Genoa money owners into borrowing and lending. In the accounts payable module, debit records the money owed to customers, credit records the money returned to customers, and the difference is the money that has not been returned. That is, the borrower's balance is how much he still owes the customer that month.

To sum up: depositors' deposits in banks are liabilities to banks.