If you have an iPhone 6 or iPhone 6 Plus, you can use Apple Pay to make purchases in stores by tapping your phone on special near field communication (NFC) pads. A lot of major retailers like Walgreens, McDonald's, and Whole Foods support it. But keep in mind a majority of stores do not accept Apple Pay, so you won't be leaving your regular wallet at home any time soon.
I tested Apple Pay at a Walgreens, and it worked perfectly. Was it easier or faster than swiping a credit card? Not really. But I'll have to spend some more time testing it before I can really judge Apple Pay's value.
In the meantime though, here's how you set up and use Apple Pay.