What is touch user interface?
A touch user interface is a computer-pointing technology based upon the sense of touch (haptics).
Whereas a graphical user interface (GUI) relies upon the sense of sight, a touch UI enables not only the sense of touch to innervate and activate computer-based functions, it also allows the user, particularly those with visual impairments, an added level of interaction based upon tactile or Braille input.
When the term touch UI is related to the touchscreen, we are referring to multi-touch technology.
Most of the apps and games that use this technology have optimized for touch UI due to the large use of touchscreens.