It is practically impossible to record all transactions in one book of prime entry. Hence, the journal is sub-divided into a number of subsidiary books. These are also called special journals. The sub-division is done in such a way that a separate book is used for each type of transactions which are repetitive in nature and are sufficiently large in number, In any large business the subsidiary books generally used are as follows :

1. Cash Book: It is used for recording all cash receipts and cash payments including cash purchases and cash sales.
2. Purchases Journal: It is used for recording all credit purchases of goods.
3. Sales Journal: It is used for recording all credit sale of goods.
4. Purchases Returns Journal: It is used for recording the returns of goods to suppliers. It is also known as 'Returns Outwards Book'.
5. Sales Returns Journal: It is used for recording the returns of goods by customers. It is also known as 'Returns Inwards Book’.
6. Bills Receivable Journal: This book is meant for recording transactions relating to bills of exchange and promissory notes received from debtors.
7. Bills Payable Journal: This book is meant for recording bills of exchange and promissory notes accepted by the business in favor of creditors.
8. Journal Proper: In this book only such transactions are recorded which are not covered, by any of the above named subsidiary books, for example, credit purchases of fixed assets, opening entry, rectification entries, etc.

The advantages of having a number of subsidiary books as listed above are as follows :

1. Classification of transactions becomes automatic: As there is a separate book for each type of transactions, the transactions of same nature are automatically brought at one place. For example, all credit purchases of goods are recorded in the Purchases Journal and all credit sales are recorded in the Sales Journal.
2. Reference becomes easy: If any reference is required, it can be traced easily by referring to the appropriate subsidiary book. You do not have to go through all the transactions recorded in the journal.
3. Facilitate division of work: Sub-division of journal into various subsidiary books facilitates division of work among many persons. This, in turn, facilitates prompt recording of transactions and saves a lot of time.
4. More particulars: More details about the transactions can be given in subsidiary books than would be possible in one book.
5. Responsibility can be fixed: The work of maintaining a particular book can be entrusted to a particular person. He will be responsible for keeping it up-to-date and in order.
6. Facilitates checking: When the Trial Balance does not agree, the location of errors will be relatively easy.