The principle of book-keeping by double entry is the complete recording of every transaction as it occurs in a. System which is composed of a number of accounts. An Account is simply a statement of a set of monetary transactions, classified in a convenient form to show the effect of each transaction, and of the transactions as a whole, on the business. The usual form of Account is as follows:–The left-hand side is called the Debit side, and the right-hand side the Credit side. All monetary transactions, involving as they do an exchange of one kind of property for another, can only be completely recorded by two entries in the Accounts, the one debiting the Account which receives the benefit, and the other crediting the Account which imparts the benefit.