Apple Pay is a payment system designed to change the way you shop. The company has been leading the way in the effort to move consumers from physical wallets packed with cards to a world in which your iPhone or Watch does all the work.

We've combed through all the technical details and complexities involved with Apple Pay to give you an easy-to-read summarisation. Take a moment to read on because Apple Pay will certainly change how you pay and it's worth knowing all about it so you aren't caught short.

READ: Apple Pay hands-on: Shopping with your iPhone

Apple Pay is a contact payment technology as well as a feature on the latest iPhones and Apple Watch. It pulls your credit cards, debit cards, and other sensitive-payment data from the Wallet app, enabling you to use an iPhone 6, 6S, SE or Apple Watch as a wallet at store checkouts.

USA

Apple Pay initially became available in the US. It debuted on 20 October 2014.

UK

Apple Pay launched in the UK in July 2015, about 9 months after its initial debut.

Europe

Apple Pay is available in the US, UK, Canada, Australia and China.

Job listings (via MacRumours) have indicated Apple Pay might expand to Europe, Middle East, India, and Africa. Apple has not confirmed any launch dates or regions in regards to international availability, however.

Apple Pay works with iPhone 6 or iPhone 6 Plus and later (Apple Pay in stores and within apps), iPad Pro, iPad Air 2, or iPad mini 3 and later (Apple Pay within apps), and Apple Watch (when paired with iPhone 5 or later).

Apple Pay supports most major credit and debit cards providers and US banks.

It works with Visa, MasterCard, and American Express cards from financial institutions (like American Express, Bank of America, Capital One, Chase, Citi, and Wells Fargo). Other companies adding support soon include Barclays, USAA, Navy Federal Credit Union, PNC, and US Bank.

For the UK, Apple Pay works with M&S Bank, Bank of Scotland, Barclays, Halifax, Ulster Bank, NatWest, American Express, Santander, Royal Bank of Scotland, Nationwide, HSBC, First Direct, TSB, MBNA and Lloyds Bank.

Here is a list of every bank that supports Apple Pay in the US, UK, Canada, Australia and China.

Yes. The White House announced on 13 February that Apple's mobile-payment system would work with federal-payment cards, including Social Security and veterans benefits that are paid through debit cards.

The deal includes the Direct Express payment network and government cards issued through GSA SmartPay. Tim Cook, Apple's CEO, also said Apple Pay would support transactions with the federal government by September, meaning you'll be able to use Apple Pay to buy tickets and gift shop items at national parks, etc.

It's worth noting that, by making this announcement at the White House Cyber Security Summit, the US government is officially admitting it is confident in Apple Pay's security capabilities, and thus more governments from around the globe might soon add support for Apple Pay.

Apple Pay works anywhere that accepts contactless payments, which includes over a million stores. Just look for the contactless payments symbol near readers at checkout.

A few of the US stores and restaurants that accept Apple Pay include: Babies-R-Us, Bloomingdales, Disney, Duane Reade, Macy's, McDonalds, Nike, Petco, Staples, Subway, Toys-R-Us, Unleashed, Walgreens, Whole Foods, etc. You can find a complete list here.

The UK already has an established contactless payment system, and you'll be able to use Apple pay at many of the stores and restaurants you already do, including: Boots, Bill's. Dune, Waitrose, M&S, Wagamama, Nando's, Liberty, Lidl. A full list is available here.

You can also use Apple Pay within many apps. For example, to pay for your British Airways flights through the app.

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iPhone/iPad

You need to use Apple's Wallet app to setup Apple Pay, or rather store your credit cards and debit cards. Apple Pay pulls this data to pay for goods.

On your iPhone, open Wallet. On your iPad, go to Settings > Wallet & Apple Pay. Tap Add Credit or Debit Card. If your card is already on file with iTunes, enter the card's security code. Otherwise, you can use your device's camera to capture the information on your credit, debit, or store card. Then fill in any additional information needed.

Your bank will verify your information. You may need to provide additional verification. After your card is verified, tap Next, and then you can start using Apple Pay.

Watch

To setup Apple Pay on the Watch app on your iPhone, open the Watch app on your iPhone, then tap the My Watch tab, and tap Wallet & Apple Pay. Tap Add next to the card that you want to add.

Your bank will verify your information. You may need to provide additional verification. You'll receive a notification on your Apple Watch that your card is ready for Apple Pay.

Apps

Apple Pay has an API, so it isn't just limited to physical retail locations. You'll be able to use Apple Pay to purchase things through apps. For example, in the UK, British Airways supports Apple Pay, so once you select your flight, you can pay from the iPhone without having to plug in your card details.

Checking out is as easy as selecting Apple Pay and placing your finger on Touch ID.

iPhone

Apple Pay requires the Near Field Communication antenna and Touch ID on iPhone 6 and later.

To pay at checkout, just hold your iPhone near a contactless reader with your finger on Touch ID. You won't have to look at your iPhone's screen, because a subtle vibration and beep will confirm that you paid correctly. There's also no need to open an app or wake your iPhone's display.

Your fingerprint confirms the payment, or you could enter a passcode if you haven't setup Touch ID. Once approved, a receipt is recorded in the Wallet app so you can see what you've purchased.

Watch

To pay at checkout, double-click the button below the Digital Crown on Watch while also holding the face of Watch near a contactless reader. Similar to Apple Pay for iPhone, a pulse and beep will confirm that your payment information sent.

Apps

Apple iPhone apps can also integrate with Apple Pay, meaning you will be able to select Apple Pay at checkout when ordering anything from an app. You also still need to place your finger on Touch ID when paying.

Some of the apps that currently support Apple Pay include: Groupon, MLB, OpenTable, Panera, Sephora, Starbucks, Target, Ticket.scom, Uber, and more. The full list is available here.

Yes. Apple said it doesn't save your transaction information or card numbers on its servers, though your most recent purchases are kept in the Wallet app.

Apple Pay, which has a tokenised backend infrastructure, makes card payments secure by creating a number or token that replaces your card details. More specifically, it creates a Device Account Number for each one of your cards.

According to Apple, the Device Account Number is assigned, encrypted, and securely stored in the Secure Element, a dedicated chip in iPhone and Apple Watch, and when a payment is initiated, the token is passed to the retailer or merchant. The retailer or merchant therefore never has direct access to your card details.

Apple

Losing your iPhone or Watch is stressful enough, but with Apple Pay, the chances of that happening just got a lot more frightening. But it doesn't have to be that way, in Apple's opinion.

The company said you can use Find My iPhone to put your device in Lost Mode. This will lock everything and prevent others from accessing your content including Apple Pay or Wallet data.

Alternatively, you can use Find My iPhone to wipe your iPhone clean completely. 

Apple has this website that details how to set up and use Apple Pay.