A debit is an accounting entry that either increases an asset or expense account, or decreases a liability or equity account. It is positioned to the left in an accounting entry. The reverse of a debit is a credit.
In double entry bookkeeping, the total amount of debits entered in an accounting transaction should match the total amount of credits entered. The result is considered a balanced transaction. If there is an imbalance between the debit and credit totals, then financial statements cannot be produced.