AR and VR

Augmented reality (AR) lays digitally created graphics, information or 3D models over live video of the real world. Virtual reality (VR) creates a completely computer-generated world for you to explore.

In AR, the device's camera films what is in front of you. As the camera moves, the software uses what it can see to work out where the virtual object should sit, how big it should look and which way it should face. This is why a 3D model of a heart can seem to hover above a textbook page and stay in place as you move your phone around it.

AR in use

• Museum: an app could show the name and diet of each dinosaur skeleton as you point your phone at it.
• Car repair: a mechanic's app could highlight the dipstick and draw an arrow to show which way to pull it.
• Music practice: a guitar app could place coloured dots on the fretboard to show where your fingers go for a chord.

AR is also used for navigation, retail try-on (seeing how a product looks before you buy it), sport broadcasts and entertainment. AR adds to the real world, so you can still see everything around you.

VR and how it differs from AR

VR usually needs a special headset. The headset shows a world made entirely by a computer and blocks out the room around you, so the real world is replaced rather than added to. A geography lesson, for example, could let you look around a computer-generated rainforest.

The key difference is that AR adds digital content to the real world, while VR replaces the real world with a computer-generated one.