Google goog is buying Eyefluence, a company that specializes in eye-tracking technology that in its commercial form helps users navigate inside augmented reality (AR) and virtual reality (VR) applications. Terms were not disclosed.

Three-year-old Eyefluence, which is based in Milpitas, Calif., disclosed the news on its website where it was first spotted by Mattermark. Eyefluence had raised about $21.6 million in funding from the venture capital arms of Intel intc , Motorola msi , and others.

The company is working on software that can be incorporated into AR/VR headgear and smart glasses like Google Glass.

Last year, Eyefluence chief executive and co-founder Jim Marggraff told Fortune sister publication Time that “eye interaction” software can enable better control-and-command of computer gear. “Imagine being able to do anything you can do with your finger on a smartphone or tablet, but only using your eyes,” he said. “Navigating data, zooming on content, and getting information is much faster when you can instantly access it by looking at it.”

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And it’s not just about fun-and-games. This sort of technology can enable service technicians to view maintenance and repair manuals or videos via their glasses or headsets while keeping their hands free to perform the work.

Augmented reality blends elements of the real-life physical world with other made-up or “virtual” objects. On the gaming front, Pokemon Go is an example of augmented reality because the computer-generated cartoon images seemingly appear in real places on the player’s smartphone.

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By contrast, virtual reality creates a whole new world that users can view and interact with. In the business realm, the terms augmented reality (AR) and virtual reality (VR) are often used interchangeably.