Wikipedia defines a touch screen as a display overlay. A touch screen is fundamentally an input device like a mouse only with touch screens, your finger on the display screen does all the functions a mouse pointer does. By simply touching the display screen, users can perform various functions.

Interestingly, a touch screen can be used for most computer applications. If you have a touch screen display for your home computer, you will probably never need a mouse again. The technology is somewhat comparable to that used in touch pads in laptops and other computing systems. Currently, touch screens are more popular for commercial uses like touch screen kiosks and at customer support desks.

There are various kinds of touch screens. Podium touch screens, touch panels, touch kiosks and touch screen monitors are some of the many varieties of display overlays that use the touch screen technology. The technology behind touch screens is complex. These touch sensitive displays use resistive, capacitive, photosensitive, or acoustically sensitive technology. Touch-sensation is the basis of resistive technology whereas capacitive technology works through electrical sensitivity. On the other hand, photosensitive touch screens operate through infrared rays and acoustic touch screens operate on the principles or surface acoustic wave.

Touch screens are very popular in the retail environment. Here, they are useful for providing information to customers. Touch screens are attractive and customers can use them without much technical knowledge. If the touch screen is used on point of sales, the screen usually also has a stylus that can be used to enter data into the system. This is common at ATMs where you can enter account information through a stylus.

Touch screens are getting very popular as a friendlier input device. Even gaming systems and smart-phones use touch screens. The technology is quite advanced but touch screens are more expensive than regular display systems so their usage is currently limited to the commercial segment only.