Alt+Tab and Shift+Alt+Tab
For laptop users, this is faster than dealing with fingers and a touchpad to scroll through open programmes.
To alternate quickly between open applications, hit Alt and Tab keys at the same time. A list of icons of all open programmes will be shown.
Holding on to Alt, keep tapping the Tab key to cycle through the open applications. When the one that you want is higlighted, let go of both buttons and that program will appear on the screen.
By holding Shift+Alt+Tab and hitting Tab, the cursor moves backwards instead of forward.