Transaction processing switch is a longer name for a payment switch, and that entry explains the technology, its history and the companies that run switches. This page covers how the longer term is used.
A switch is the routing hub of an electronic payment system. It receives a message, such as a card authorisation request from an ATM or a shop terminal, reads the card number or account identifier, works out where the message must go, translates it into the format the recipient expects and forwards it. When the reply comes back, the switch returns it to the sender and records the transaction for clearing and settlement. Switches typically handle very high volumes with strict limits on delay and downtime.
The phrase "transaction processing switch" is common in technical specifications, vendor documentation and central bank material, where it helps distinguish the switching function from other parts of processing, such as authorising on behalf of an issuer or keeping account balances. A national switch connects banks inside one country, often run by or for the central bank, and may support interoperability between card schemes, mobile money and bank accounts. Shared ATM and debit systems such as an electronic funds transfer network depend on switches, as do card schemes, acquirers and processors.