Windows 8 introduces a new touch paradigm that is different from other touch devices on the market. To help you get started I have outlined the basics of touch on Windows 8 that are used throughout the new Metro interface. Not all touch gestures are compatible with every Metro application; some are up to the developer to implement when appropriate.
Initiates the primary action of an element, such as launching an app from the Start Screen.
Tap and hold
Identify what the element is or what you can do to it.
Selects the element.
Swipe down further
Releases an element from the current position allowing movement.
Slide left or right
Drag the element across the screen after it has been released.
Swipe from the right edge of the screen inward
The Metro Interface charms will appear revealing the Search, Share, Start, Devices and Settings charms along with system time and connection information.
Swipe from the top or bottom edge inward
Displays any application specific charms the developer created on the top or bottom of the screen.
Swipe from the left edge inward
Switches to the previously launched app.
Swipe from the left edge inward and hold
Displays a preview of the previously launched app and allows you to snap it to the left quarter of the screen on release.
Optically zooms in or out on an element or exposes a different level of abstraction in applications that support Semantic Zoom. E.g. While looking at 12 month calendar, pinch zoom will change the view to a single month or day.