Glossary

Full glossary available from:
http://usa.visa.com/merchants/merchant_resources/glossary.html#glossary2
http://www.mastercard.com/us/merchant/assistance/glossary.html

Interchange Systems

Networks that act as authorization service for Visa and MasterCard transactions as wells as settlement service to transfer information between Issuers and acquires.

Payment Application

System that creates a card transaction

Merchant

Company that accepts card payments

Issuer

Financial institution that issues Visa or MasterCard cards to card holders