It contains printed forms which are used for depositing cash and cheques into the bank. Look at the form of a pay-in-slip. The first part is called counterfoil and the second part is the main pay-in-slip. When you submit it to the bank along with the amount to be deposited, the bank will stamp and sign the counterfoil and give it back to you. The main pay-in-slip is retained by the bank for further processing. The counterfoil is for your own record and future reference. The cash book entry for deposit is also made with the help of the counterfoil.