Contactless payment is any payment made without physical contact between a card and a reader, usually over NFC within a few centimetres. Tap to pay is its most common form.
The longer version
Contactless payment covers cards and phones that pay without being inserted or swiped. In practice it almost always means NFC, so the device still has to come within a few centimetres of the terminal. The contact is gone, but the close, aimed gesture remains.
The convenience is real and familiar, which makes contactless a useful baseline for what customers already accept. It also sets expectations. People now expect payment to be quick and to not involve handing anything over. The card side of contactless is standardized by EMVCo.
Proximity payment extends that expectation. It keeps the speed and the no contact feel, but removes the requirement to present a device at all. Presence at a wider range identifies the payer, and the money routes through a server instead of across the terminal.
The Parousya method
Contactless payment is the experience customers already trust, and the Parousya method builds on it. The method removes the last gesture, so recognition happens by presence rather than by bringing a device to a reader.