Under double entry system transactions are first of all recorded in journal and thereafter posted to ledger. As you might now that the 'Ledger' is the main book of account. The book which gives additional help to the main book (Ledger) is called subsidiary book. Thus the journal is a subsidiary book and the ledger is a main book. The 'Journal' is an old French word meaning 'Daily Record', and it is called so because everything that happened everyday is recorded into the book at once, before the exact details of transaction are forgotten. It is in the journal that the 'original documents' (Invoices etc.) are recorded. In small business concerns only one journal and one ledger may serve the purpose, because the number of transactions is very small. But in large business concerns the number of transactions are numerous, just one journal and one ledger will not do the job. That will cause much inconvenience i.e., If we have only one journal in a large scale business, it is not possible only for one book-keeper to record all the transactions in time. On the other hand, it will not be possible for more than one person to use the same journal simultaneously with the result that the accounting work will fall in arrear. Thus in a large business concern a journal is divided into parts so that several clerks could work at the same time. This is known as %E