The headset appears to combine virtual reality, augmented reality and live video to offer a new computing experience.
See it in action,
The biggest difference between the HoloLens and other devices (like, say, the Oculus Rift or the Gear VR) is that, with no need for an outside computer or mobile device. That could be the key to making the HoloLens a default winner in these early days of augmented-virtual-reality systems.
The front is a see-through, shaded lens cover; the side arms include spatial sound, adding to its three-dimensionality. The headset doesn't come with any wires hanging off the back, indicating that it will be a wireless experience — again, a very powerful distinction from the competition.
Based on a quick look at the headset, it appears to have four front-facing cameras that could be used to detect the positions of the user's hands as interacts with holographic objects.
In addition to creating objects, the headset will be usable for gaming and even collaborating remotely. For example, Microsoft showed off "holographic" interactions on the surface of Mars; according to one NASA staffer in the presentation video, the space agency hopes to put the headset into use this summer.
Of course, the "holo" name is a bit deceptive, as this is more of an augmented reality system than a truly holographic system.