Internet Payment System

A formally defined system intended to service financial transactions between business partners that uses the Internet as its means of communicating transactions and their details (an online resource listing many different kinds of Internet-based payment systems is locate here).

Electronic Financial Transaction System

A formally defined system intended to service financial transactions between business partners that does not necessarily use the Internet as its means of communicating transaction details (see Datapac).  There is also a listing of non-Internet based transaction systems here.

Digital Cash

Digital cash refers to any number of electronic funds settlement services, either ones that fit into the existing EFT scheme or those who propose to create their own currency, somehow convertible to cash after withdrawal process of some kind (see Paypal, Bidpay)

Electronic Cheque

"The Electronic Check is just what its name implies: an electronic substitute for the paper check. Like paper checks, Electronic Checks are legally binding promises to pay. In place of the handwritten signature on a paper check, the Electronic Check uses a digital signature (see note below for an explanation of digital signatures) that can be automatically verified for authenticity." echeck.commerce.net

More information on electronic checks (US spelling) is available at eCheck.

Smart Cards

There are many credit-card shaped objects referred to as "smart cards".  Partially this is the fault of the vendors of various kinds of cards (see Gemplus, Schlumberger, Sun) who for the most part are willing to do anything to sell their products into a definitely soft market, partially it has to do with a lack of a clear definition.  Smart cards are by definition possessed of processing capability, unlike the cards we all currently carry, that only serve as stored value cards, smart cards feature a resident microprocessor, memory and either an induction loop (contactless) or landing pad (contact) to power the card.  Smart Cards are portable, non-powered, special purpose security microcomputers.

Internet Keyed Payment Protocol (iKP)

A precursor to Secure Electronic Transactions (SET), iKP was donated by IBM to the IETF task force created to define a standard method of settling financial transactions on the Internet.  At the time there were several initiatives in place, notably by Netscape and Cybercash - one version of the story of the evolution of iKP to SET is detailed here:

Secure Electronic Transaction Protocol (SET)

"In February 1996, MasterCard and VISA, with support from IBM and other technology partners, announced that they had agreed on a new standard for secure Internet protocols - a convergence of STT and SEPP - known as Secure Electronic Transactions [SET]."  www.ibm.com

An extensive history of the pedigree of SET is available here.

"A protocol defined by The SET™ Specification (download); an open technical standard for the commerce industry developed by Visa and MasterCard as a way to facilitate secure payment card transactions over the Internet." www.setco.org