From today more than 250,000 shops across the UK will begin accepting Apple Pay payments, including Boots, the Post Office, Marks & Spencer, Waitrose and London’s transportation network Transport for London (TfL).

Users of Apple’s NFC enabled devices can now use them to make contactless payments in retail stores as well as in-app and online purchases. This includes those who own the iPhone 6 and iPhone 6 Plus (shops and in-app payments), the Apple Watch (shops payments), iPad Air 2 and iPad mini 3 (in-app payments).

Instead of storing credit or debit card numbers on the device, a unique device account number is assigned and stored securely in a dedicated chip within the device called “the Secure Element”. Card numbers are not stored on Apple’s servers, and only the device account number is used when processing the payment. To add security, should a device be lost or stolen, Apple’s “Find my iPhone” feature allows the user to put the device in “Lost mode” to lock the device and keep track of its location, or wipe all data from the device entirely.

The Apple Pay app uses the iPhone 6’s in-built fingerprint scanner and Near Field Communication (NFC) chip to make payments when in range of a store’s NFC payment equipment and by pressing and holding the iPhone’s Home button. This will automatically open the Apple Pay app where users can select a previously registered payment card to pay for the transaction.

When paying using the Apple Watch, users double tap the side button which will display payment cards previously registered and make their selection. When a payment is complete, like the iPhone, the Watch will vibrate.

Visa, MasterCard and American Express cards can all be used to make purchases using Apple Pay, and the following banks are participating:

Image courtesy of Apple

Apple Pay has been available in the US since October 2014 and, according to Apple’s Chief Executive Time Cook, more than 1 million credit cards were registered within three days of its launch, making it, he claims, the largest mobile payment system to date.

According to research firm KantarWorldPanel, there are currently 2.9 million Apple Pay compatible devices in use in the UK, although this figure can be increased when considering that older handsets can be used if paired with the smartwatch.

Currently, the UK limit for contactless payments is £20, but this is due to increase to £30 this September.

Watch Apple’s demo video of using the Apple Pay with the iPhone and Apple Watch: