The system of keeping accounts in which, as a check on accuracy and consistency, every payment appears twice, in different accounts, once as a credit and once as a debit. Thus a sale appears as a credit for the department making it, and a debit for the customer, while a purchase appears as a debit for the department making it and a credit for the supplier. Double entry books can if desired be represented in a single table, using rows for credits and columns for debits. As a check on double entry accounts, every debit item must have a corresponding credit, and the totals of all credit and debit entries must be equal.