A more thorough explanation:

Definition: A waste book is a book used by merchants to record rough entries of transactions before posting them into a journal. It is also known as a blotter.

Example: A shopkeeper uses a waste book to jot down the details of all the sales made during the day. Later, the shopkeeper will transfer these entries to the shop's official journal.

Explanation: The waste book is used to keep track of transactions before they are officially recorded in the journal. This helps the merchant to keep a record of all transactions and ensure that nothing is missed. The waste book is also useful for making quick notes and rough calculations, which can be refined later when the entries are transferred to the journal.