Gateway: the technical doorway
A payment gateway receives and securely transmits payment information between the merchant’s checkout and its payment infrastructure. “Gate” is common informal shorthand. A gateway integration does not, on its own, tell you which institution acquires the transaction.
Processor and acquirer: connected, not identical
The processor handles transaction messaging and processing. The acquirer supports merchant acceptance and the acquiring side of the payment relationship. One provider can package these roles together, so commercial product names do not always reveal the underlying responsibilities.
Network and issuer: routing and the customer side
The card network connects participants and supplies scheme infrastructure and rules. The issuer issued the customer’s card and typically decides whether to approve the authorisation. The merchant does not directly control that decision.
Draw the actual responsibilities
For an integration discussion, identify who owns acceptance, routing, authentication, reconciliation, disputes and payouts. Ask which organisation performs each role in your contract. The same logo can cover several functions; the same checkout can use several providers.