The Double Entry Principle

Double entry accounting, also called double entry bookkeeping, is the accounting system that requires every business transaction or event to be recorded in at least two accounts. This is the same concept behind the accounting equation. Every debit that is recorded must be matched with a credit. In other words, debits and credits must also be equal in every accounting transaction and in their total.

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concept of double entry just click on the link  and watch the tutorial.