Apple Pay on websites launched on Tuesday with the release of iOS 10 for the iPhone and iPad — and will hit Mac desktops when macOS Sierra launches next Tuesday.More than 200,000 websites — including small and large retailers — plan to support Apple Pay on their sites in coming weeks, Apple said Tuesday. Many of the sites include online retailers using e-commerce platforms run by Shopify, Demandware and IBM. The move means that online shoppers with iPhones, iPads and Macs updated with the latest operating systems can save time when finishing an online purchase through the Apple’s Safari browser. Retailers that have signed up for the service are expected to see an uptick in the number of customers that finish a web purchase, instead of giving up because typing in credit information was considered too complicated, awkward or time-consuming.Apple first revealed the new feature in June at WWDC and recently posted a support page describing how Apple Pay has moved beyond in-store payments and in-app payments to website payments.The nitty gritty detailsHere’s how it works: After searching out a product or service in Safari to purchase, Apple Pay customers need only click an Apple Pay button on a website to complete their purchase.For Mac desktops or laptops, after the pay button is clicked, a buyer will authenticate the purchase with a fingerprint scan on their iPhone or a double touch on their Apple Watch. Once Sierra is available, a Mac user must be signed in to the same iCloud account on the iPhone or Apple Watch as on the Mac, and Bluetooth must be enabled on the Mac, Apple said.