iPhone users have been able to use their phone to make payments at various outlets (most notably on the London underground) for a while now. Now Google have introduced a similar feature to Android.
For those that are unaware, this system works in a very similar manner to contactless debit / credit cards that have been issued by many banks now. Once you've setup the payment app, you just wave your phone at the payment terminal, and for purchases less than £30, the payment is instantly taken. For higher values (where this is supported by the retailer), you will need to unlock your phone in your usual manner (whatever that might be - PIN, pattern or fingerprint). This is to avoid large purchases being made without permission using a stolen phone.
However, unlike Apple devices, the situation on Android devices isn't entirely straightforward. Apple do not allow any 3rd party the access the bit of the phone that enables these payments to work. Therefore, if you are an iPhone user, you have no choice but to use Apple's app to make payments in this manner.
Android, being a much more open system, allows 3rd parties to access every bit of the phone. This means that other providers are able to offer their own payment apps which will work equally well at these payment terminals. While this does promote healthy competition between the various providers, it also makes the picture more confusing.
Most people will be able to use the Android payment app. However, Barclays Bank customers will find that their cards don't work. They will have to wait until Barclays release their own payment app. Also, Samsung are releasing their own app (Samsung Pay) which will also support most (but not all) cards.
Currently, very few payments are being made in this manner. However, contactless debit cards took a while to gain traction, so both Apple and Google are hoping that use of their payment apps will pick up in a similar fashion in the coming months