Apple explains which adapters will fast-charge the iPhone 8

Yes, Apple's new iPhone 8 and iPhone 8 Plus support fast charging. No, you don't get this functionality out of the box — you need to purchase a separate charger. 

But it doesn't have to be an original Apple charger. According to Apple's support page on the matter (first spotted by MacRumors), you can use a "comparable" third-party USB-C power adapter, as long as it's certified for USB Power Delivery. 

The page doesn't mention the iPhone X, but it's safe to assume that the above is valid for it as well. 

To check whether a third-party charger will work with one of the new iPhones, read the information that's usually written on the adapter itself. It should say "USB PD" somewhere on there, and the other specs should be similar to the ones on Apple's Type-C USB power adapters (see below).  Read more...