When a transaction takes place in a business firm then accountant prepares a suitable voucher as per the nature of transaction .  After the vouchers are prepared then these vouchers are recorded in a book on daily basis. This book is called as day book or journal book.

The day book is called as subsidiary book or primary book also because the transactions are recorded in day book first. In small companies single day book is kept for recording all types of vouchers but in a big organization it is not possible to record so many transactions in a single day book or by a single person. Therefore,  day book is divided into different special day books according to the transactions of the company and the work also can be divided into different accountants as per the nature of transactions.

Normally, the following types of day books are maintained in a big business firm:-

  1. Cash day book:– to record the cash vouchers only.
  2. Bank day book:- to record the bank vouchers only.
  3. Purchase day book:– to record the credit purchase vouchers only.
  4. Sales day book:- to record the credit sales vouchers only.
  5. Purchase return day book:- to record the purchase return vouchers only.
  6. Sales return day book:- to record the sales return vouchers only.
  7. General journal register or Journal book:- to record the vouchers other than   above vouchers.