Simultaneous Localization and Mapping
Simultaneous Localization and Mapping (SLAM) is the computational problem of constructing or updating a map of an unknown environment while simultaneously keeping track of an agents location within it.
A system originating from robotics and computer vision, SLAM is a procedure by which a computer scans an environment and constructs a digital map of the area. This has become a standard for anchoring augmented reality content in real world, physical spaces. This is the process Apple ARKit apps undertake to detect surfaces.