Touch-based interfaces have unique considerations that do not apply to other modes of input, and vice versa.
Touch-based interfaces are found on devices such as tablet PCs and touch-screen smartphones. The touch interfaces common today use capacitive technology designed to work well with simple finger touches. (Older, pressure-sensitive displays require the use of a stylus for accurate input.)
While touch input is similar to other two-dimensional input methods such as mice and drawing tablets, it lacks some characteristics of those other devices that are often taken for granted. For example, an on-screen cursor can be moved with a mouse to "hover" over an object without selecting it; there is no analogue to this in a touch interface because the act of pointing and selecting are both defined by a single touch.
Conversely, it is possible to do some kinds of input via touch that are difficult or impossible to represent with something like a mouse. In particular, modern "multitouch" interfaces allow two fingers to be used for pinching or stretching. Also, two or more fingers may be used to augment normal touching and dragging gestures (though this is analogous to using a mouse with alternate buttons or keyboard modifiers).
