Answer briefly the following questions : A voucher is essentially the backup document/proof for a transaction. How is it important for banking transactions?

A voucher is essentially the backup document/proof for a transaction. The banks when debit or credit the customer's or other accounts, the customers or their details of the transaction is noted on a piece of paper (approved format by the bank) which is called as voucher. Examples - paying-in-slip, cheques, office debit and credit vouchers used for their internal transactions (these do not have counterfoils). They serve as documentary evidence for a transaction. Office debit/credit vouchers are to be authenticated by sanctioning authority before the transaction is entered the system.