ARKit is Apple's new framework for creating augmented reality experiences on iOS 11 devices using only the iPhone's single camera and sensors. It allows developers to build AR apps for over 100 million iOS devices without needing additional resources like image triggers. ARKit uses technologies like visual-inertial odometry and scene understanding to detect horizontal planes and place virtual objects that are estimated to scale in the real world. Popular game engines like Unity and Unreal are supporting ARKit integration to make development easier.