Debit is an accounting and bookkeeping term that comes from the Latin word debere which means "to owe." The opposite of a debit is a credit. Debit is abbreviated Dr while credit is abbreviated Cr.

A debit changes the balance of an account. Asset and expense accounts increase in value when debited, whereas liability, capital, and revenue accounts decrease in value when debited. This distinction is somewhat counterintuative, until the nature of those accounts is more closely scrutinized. For example, revenue is coded as a credit. After recording a day's sales, the company will have credited a certain amount in revenue, and since credits are negative numbers, the balance grows more and more negative (further away from zero on the number line in the negative direction.) An adjustment to revenue would need to be a debit, because its purpose it to bring the revenue totals closer to zero.

For instance, the journal entry for paying the telephone bill might look like this:

The telephone company would record the exact same transaction (from their side) like this:

Many people who have no formal education in Accounting often assume that a debit decreases a balance because use of a bank's debit card decreases the balance in the customer's account. However, it is called a debit card because, from the bank's perspective the customer's account is a liability. By withdrawing money, the customer is decreasing the bank's liability. Since liability accounts normally have a credit balance, the withdrawal of cash from a banking account debits the bank's balance sheet.