In a four-party scheme (also referred to as [[Four Corners Model for Payment Security|Four Corners Model]]), the issuer and acquirer are different entities, and this type of scheme is open for other institutions to join and issue their own cards. This is the type of card scheme used by [[brand]]s such as [[Visa Inc.|Visa]], [[Mastercard]], [[Verve Card]], [[UnionPay]] and [[RuPay]]. There are no limitations as to who may join the scheme, as long as the requirements of the scheme are met.
==Processes==
The card scheme utilizesuses the respective [[guideline]]s<ref name="Mastercard Rules">{{cite web |last1=Summary of changes 2020 |title=Mastercard card scheme - Rules and guidelines |url=https://www.mastercard.us/content/dam/mccom/global/documents/mastercard-rules.pdf |publisher=Mastercard |date=December 2020 |access-date=2021-08-23 |archive-date=2021-08-23 |archive-url=https://web.archive.org/web/20210823112149/https://www.mastercard.us/content/dam/mccom/global/documents/mastercard-rules.pdf |url-status=dead }}</ref><ref name="Visa Rules">{{cite web |last1=Visa core rules 2021 |title=Visa card scheme - Product and service rules |url=https://sr.visa.com/content/dam/VCOM/download/about-visa/visa-rules-public.pdf |publisher=Visa |date=April 2021}}</ref> to process the card exchange data from the acquiring to the [[issuing bank]], and vice versa, until the [[payment]]<ref name="Payments industry ecosystem 2021">{{cite web |title=The payment industry's biggest trends in 2021 |url=https://www.insiderintelligence.com/insights/payments-ecosystem-report/ |publisher=Insider Intelligence |date=July 2021}}</ref> is fully completed (or denied). Credit and [[debit card]]s work with a four-party scheme, completing an open-circle framework that permits consistent flow of transactions; thus, allowing the banks to handle the whole process.
Card schemes aim to make the transaction convenient and automated for all parties involved in the loop, with the core belief that [[Customer|clients]] end up spending more than intended when the payment process is simple.
