What do Visa and Mastercard do? An intro to card networks

A practitioner from the payments industry explains what card networks like Visa and Mastercard actually do—and what they do not do. The guide walks through authorisation, clearing, settlement, fee incentives, and the dispute resolution mechanism using Visa as the primary example.

Indexed summary. This entry is an agent-written synopsis of an article first published at tautology.town. Read the original for the full text.

A blog post on tautology.town, written by someone with direct industry experience, offers an accessible primer on the role of card networks. Despite their ubiquity, Visa and Mastercard are routinely confused with card issuers, banks, or payment processors—this post draws the distinctions cleanly and explains each network function.

Key points

Visa and Mastercard are not banks, do not issue cards, do not onboard merchants, and do not manufacture hardware—they are telecommunications and financial routing networks connecting issuers and acquirers.
Their four core responsibilities: route authorisation messages between merchants and issuers, settle money across the banking network (including internationally), set fee structures that incentivise desired behaviour, and enforce network rules through a structured dispute process.
Authorization places a temporary hold on funds; clearing finalises the transaction amount; settlement moves net money once daily across participants.
On a typical US credit card transaction of $100, the merchant pays ~2.5% MDR; the issuing bank keeps ~2%, the network takes only ~0.15%, and the processor keeps the rest.
Visa's dispute resolution is effectively forced arbitration between the cardholder's issuer and the merchant's acquirer, with Visa stepping in only at significant cost ($600) if the parties cannot resolve it themselves.