Gesture
If Gaze is the mouse movement, Gesture is the left-click. Microsoft has done a great job of keeping this control scheme simple yet powerful. There are a few gestures that the HoloLens understands: Air-tap, Air-tap and hold, and Bloom.
Bloom has a reserved purpose: to exit applications and to open the main menu system. Due to this, developers cannot currently do anything else with it. This leaves us with two primary gestures to work with: air-tap and air-tap and hold.
The HoloLens uses its large forward-facing sensor array to track the position of both hands when they are in front of the device. When one or both hands are in viewing range, the HoloLens looks for either hand in a ready state--your index finger pointed upward at a 45-degree angle or higher.
The gestures used are just combinations of these states. Air-tap goes from ready to pressed back to ready in a fluid movement, whereas air-tap and hold goes from ready to pressed and holding.
Soon, using combinations of these states...