https://www.theverge.com/circuitbreaker/2017/9/13/16301660/apple-iphone-8-x-fast-charging-usb-c-power-charger

Tucked in among the details for the iPhone 8 and iPhone X is the fact that the new devices will support fast charging. Apple claims its new phones can recharge up to 50 percent of their battery life in a 30-minute charge. But there's a catch: you have to use USB-C, as spotted by 9to5Mac.

That's because Apple is using USB Power Delivery — one of the various USB-C charging specifications — to provide fast charging on the new phones. It's a feature the company has also offered on its newest iPads as well; both the 10.5-inch iPad Pro and the updated 12.9-inch model supported the option when they were released earlier this year. And it's hard to fault Apple for actually adhering to an industry standard here, instead of coming up with its own proprietary method.