Touchscreen

A touch screen (also called touchscreen) is a screen that can also be used as an input device for a computer or embedded system (such as a smartphone or tablet) by touching the screen with your finger or a special pen. The very first touch screen was developed in CERN in the 70s because the machines became too complex with the many buttons needed for the different functions. 
Apart from the specific technique of the screen, the software is needed to interpret the touch. This is more complex than the keyboard driver. For example:
accidental touches are filtered out,
*the touched area, which can vary greatly in size, is compared with the virtual keys,
*short breaks in the touch must be interpreted as a coincidence or as a "double-tap"
*etc.
==Advantages of touch technology==
No pointing device or keyboard is required. Even if a keyboard is present, the link between a location on the screen that is touched and the same location on the screen that indicates an option is more direct than an indication such as "for X key Y".
Compared to a keyboard specific to a specific application (with option keys), software-based options are more flexible, and more options can be built-in (compare for a ticket machine for train tickets having a key per station, with calling up station names on screen).
Scrolling texts and plans by moving a finger across the screen is also an intuitive act that resembles the shifting of a sheet of paper. Often it is built in that when one takes the finger off the screen, inertia and friction are simulated: scrolling continues for a while, but gradually comes to a halt.
==Limitations:==
Entering texts via the screen is slower than with a real keyboard. Especially for someone who has experience with a keyboard, the difference is big.
The driver needs time to interpret the touches, keeping an eye on people not going too fast requires a lot of concentration from the user.
Another problem is that the user's fingers are often thicker than the buttons on the touch screen, making it difficult to tap the right button exactly.
==Applications:==
The touch screen is often used on smartphones, tablet PCs, navigation systems and other devices where space is limited but is also used on larger screens.
The touch screen is also used in, for example, ticket machines and in cash registers of cafés and cafeterias. The touch screen is more practical in these applications than, for example, a supermarket, where the range is larger.
Another example is the use of the touch screen in a museum to call up images of works of art, objects, photos or other materials.
One of the first places where touch screens were introduced on a large scale in the Netherlands was in the mid-80s in the renewed Rotterdam Library. The screens replaced the paper catalog and the screens gave a monochrome, green image.