Payment Terminal
In short: A payment terminal reads cards or smartphones and handles the card payment.
In more detail: It supports chip and PIN, magnetic stripe and contactless payment with NFC.
In Depth
Parties involved
Merchants, terminal operators, payment service providers (Stripe, PayPal and others) and card organisations (Visa, Mastercard, Maestro).
Security
PCI DSS governs the secure handling of card data. See card readers.
See also: Card Readers, NFC, Visa, Mastercard