Here, the double entry book-keeping requires two books for it to carry out operation effectively. Those books are the journal and the ledger. Journal is defined as a book that contains private records of events as they occur day in and day out
A journal performs so many functions as thus:
(i) It serves as a diary where business transactions are recorded as they occur
(ii) It serves as a book of explanation since it requires a brief explanatory note called a narration
(iii) It serves as a book of instructions since it states which of the accounts requires a debit entry and which of them requires a credit entry