ACH A central clearing facility, operated by an ACH Operator on behalf of depository financial institutions, in which participating DFIs transmit or receive ACH entries. Checks Checks are cleared through organizations known as Clearing Houses or Check Clearing Houses.
Checks are the most prolific form of payment mechanism.
More info to follow. Smart Cards Smart Cards are not in particular a payment mechanism. They do however have many potential applications in the Payment System. Smart Cards can be used for such varied tasks as retaining consumer medical history to containing the means to authenticate and transmit encrypted information to a payee.