A line of credit is credit source extended to a government, business or individual by a bank or other financial institution. A line of credit may take several forms, such as  overdraft protection, demand loan, special purpose, export packing credit, term loan, discounting, purchase of commercial bills, traditional revolving credit card account, etc. It is effectively a source of funds that can readily be tapped at the borrower's discretion. Interest is paid only on money actually withdrawn. (However, the borrower may be required to pay an unused line fee, often an annualized percentage fee on the money not withdrawn.) Lines of credit can be secured by collateral, or may be unsecured.