# Card scheme

https://www.uniwebpay.com/glossary/card-scheme/

*Last updated: 2026-08-03*

The network a card belongs to and the rulebook both the issuer and the acquirer operate under: Visa, Mastercard, American Express, UnionPay, Diners Club and Discover are the six a Singapore merchant meets. Accepting "cards" is really accepting some subset of those six, and which subset is a commercial decision, not a technical one.

## Why it matters to a merchant

Schemes set the rules a merchant lives under without ever being a party to their contract: what a chargeback reason code means, how long a dispute window runs, what a terminal must be certified to do. A merchant who wants to know why an acquirer cannot simply waive a rule is usually looking at a scheme rule, and the honest answer from any acquirer is that it is not theirs to waive.

## Related terms

*Who does what*

- [Acquirer](https://www.uniwebpay.com/glossary/acquirer/)
- [Issuer](https://www.uniwebpay.com/glossary/issuer/)
- [Payment gateway](https://www.uniwebpay.com/glossary/payment-gateway/)
- [PSP (payment service provider)](https://www.uniwebpay.com/glossary/psp/)
- [Aggregator](https://www.uniwebpay.com/glossary/aggregator/)
- [Reseller](https://www.uniwebpay.com/glossary/reseller/)
- [Payment facilitator (PayFac)](https://www.uniwebpay.com/glossary/payment-facilitator/)
- [Payment orchestration](https://www.uniwebpay.com/glossary/payment-orchestration/)

- [All 74 terms](https://www.uniwebpay.com/glossary/)

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