You may not understand each level of the video, but the pictures paint 1000 words here as you can see the technology improvements for utilizing touch screens on mobile devices..BD
Retrieving the stylus of a pen-based device takes time and requires a second hand. Especially for short, intermittent interactions many users therefore choose to use their bare fingers instead. Although convenient, this increases targeting times and error rates. We argue that the main reason is the occlusion of the target by the user’s finger. We propose a pointing technique we call Shift that is designed to address this issue. When the user touches the screen, Shift creates a callout showing a copy of the occluded screen area and places it in a non-occluded location.
Source: shift homepage
Hat Tip: GottaBeMobile