Double-entry bookkeeping

Double-entry bookkeeping, also known as double-entry accounting, is a method of bookkeeping that relies on a two-sided accounting entry to maintain financial information. Every entry to an account requires a corresponding and opposite entry to a different account. The double-entry system has two equal and corresponding sides, known as debit and credit; this is based on the fundamental accounting principle that for every debit, there must be an equal and opposite credit. A transaction in double-entry bookkeeping always affects at least two accounts, always includes at least one debit and one credit, and always has total debits and total credits that are equal. The purpose of double-entry bookkeeping is to allow the detection of financial errors and fraud.

For example, if a business takes out a bank loan for $10,000, recording the transaction in the bank's books would require a credit of $10,000 to an asset account called "Cash", as well as a debit of $10,000 to an asset account called "Loan Receivable". For the borrowing business, the entries would be a $10,000 debit to "Cash" and a credit of $10,000 in a liability account "Loan Payable". For both entities, total equity, defined as assets minus liabilities, has not changed.

The basic entry to record this transaction in the example bank's general ledger will look like this:


	Debit	Credit
Loan Receivable	$10,000
Cash		$10,000

Double-entry bookkeeping is based on "balancing" the books, that is to say, satisfying the accounting equation. The accounting equation serves as an error detection tool; if at any point the sum of debits for all accounts does not equal the corresponding sum of credits for all accounts, an error has occurred. (However, satisfying the equation does not necessarily guarantee a lack of errors, for example, the wrong accounts could have been debited or credited.)