Using Vuforia and Unity to make an AR app
What is Vuforia?
Vuforia is a leading Augmented Reality platform, supporting Android, iOS and Unity Game Engine development platforms. It is also compatible with Hololens, Oculus Rift, Gear VR, most smartphones and tablets. Vuforia makes its SDK (Software Development Kit) available for free, requiring a registration as a developer. To download the SDK and find more info on Vuforia check out their website - developer.vuforia.com
Vuforia and Unity
Currently (December 2016) Vuforia is partnered with the Unity Game Engine and doesn't provide support for the Unreal Engine. Therefore, Unity can be used to create Augmented Reality apps that use Vuforia and will run on computers, tablets and smartphones.
Step by Step Tutorial for making a simple Augmented Reality app for Android