Vuforia Engine supports the development of space-aware AR experiences with the Positional Device Tracker. The Device Tracker provides information about where the device is relative to the world. It works well for AR applications that need to place content in the environment or want to provide additional robustness to target tracking with six degrees-of-freedom.
This article describes the use of the Device Tracker in Unity. If you are developing an application for native Android or iOS, refer to the Using the Device Tracker in Native article.