Payment terminal
The box at the till that reads the card, takes the PIN and sends an encrypted authorisation request to the acquirer.
A handful of manufacturers dominate: Verifone, founded in Hawaii in 1981, France's Ingenico from 1980, and China's PAX. A modern terminal has a chip reader, an NFC antenna and usually a magnetic-stripe reader kept around just in case. Recent generations run Android, so the merchant can install till and loyalty apps on the same device.
The expensive parts are the ones you can't see. The casing is tamper-responsive and wipes its keys if anyone opens it. Encryption keys are injected in a secure facility, often under DUKPT so that every transaction gets its own key, and the model must be certified under PCI PTS. With P2PE, card data leaves the terminal encrypted and the point-of-sale system never sees it. SoftPOS threatens the whole category by turning an ordinary phone into the terminal.