PIN debit
US debit payment confirmed with a PIN and routed over a separate network, as opposed to signature debit over Visa or Mastercard.
An American debit card has two roads. Signature debit travels over Visa's or Mastercard's rails like a credit purchase, authorised now and cleared later in a dual-message system. PIN debit goes through networks such as STAR, NYCE or Pulse, descendants of the ATM networks, which send a single message that both approves and debits. When the cashier asks "debit or credit?", the real question is which network the purchase should take.
For merchants the PIN route was long much cheaper and almost fraud-free, since a stolen magstripe is useless without the code. Hence the campaigns nudging customers to enter it, and hence the big networks' enthusiasm for signatures. Online there is no PIN pad, but so-called PINless debit lets the merchant send the purchase over a PIN network anyway, a choice the Durbin Amendment now protects.