Online card payments: who is responsible for what
One term, five different jobs. Online card payments run through a gateway, processor, acquirer, issuer and card scheme, and each one owns a specific part.
Card payments in the EU explained: PSD2, SCA and compliance

Consumer interchange is capped at 0.2% and 0.3%. Commercial cards are not. What EU card payments actually cost, and which SCA exemptions protect conversion.
Anti-money laundering in eCommerce

Money laundering in eCommerce, and why a provider’s AML program is your problem too. KYC, transaction monitoring and sanctions screening, explained.