Bill of exchange drawn on a bank and payable on demand. Checks have become the chief form of money in the domestic commerce of developed countries. As a written order to pay money, a check may be transferred from one person to another by endorsement. Most checks are not paid in currency but by the debiting and crediting of bank deposits. There are several special forms of checks. A cashier's check is issued by a bank and has unquestioned acceptability, as does a certified check, which is a depositor's check that has been guaranteed by a bank. Traveler's checks are cashier's checks sold to travelers, which must be signed twice by the payee, once when the check is issued and once when it is cashed; reimbursement is guaranteed if they are lost or stolen.