Cash book is a record of all the transactions related to cash. Examples include: expenses paid in cash, revenue collected in cash, payments made to creditors, payments received from debtors, cash deposited in bank, withdrawn of cash for office use, etc.

In double column cash book, a discount column is included on both debit and credit sides to record the discount allowed to customers and the discount received from creditors respectively.

In triple column cash book, one more column of bank is included to record all the transactions relating to bank.

Note: In modern accounting, simple cash book is the most popular way to record cash transactions. The double column cash book or three column cash book is practically for academic purpose. A separate bank book is used to record all the banking transactions as they are more than cash transactions. These days, cash is used just to meet petty and routine expenditures of an organization. In most of the organizations, the salaries of employees are paid by bank transfer.

Note: Cash book always shows debit balance, cash in hand, and a part of current assets.