How a Touch Screen Works

The touch screen technology has really taken off for quite some time now and today is the dominant input method in our phones,tablets and in some even in some laptops.Today they are used almost everywhere, from ATMs to cameras to kiosks. From being sluggish and unresponsive a few years back today the touch screens are fast and fluid. So how do they rally work. Here is a explanation for that.
Broadly there are two types of touch screen: Resistive and Capacitive.
Resistive touch screens: As the name suggest, it works on the principle of resistivity. Resistive touch technology works by sensing direct pressure.

The resistive touch screen consists of flexible top layer made of polythene and rigid bottom layer made of glass. Both the layers are spaced with spacers and are coated with indium tin oxide. When the screen is operating a small current flows in between the space. When a touch is made, the flexible screen presses down to touch the glass layer. A change in current is hence detected and coordinates of the point of touch calculated by the controller and parsed into readable signal for the operating system to react accordingly.
Capacitive Touch Screen:  In the capacitive system, a layer that stores electrical charge is placed on the glass panel of the monitor. When a user touches the monitor with his or her finger, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. This decrease is measured in circuits located at each corner of the monitor. The computer calculates, from the relative differences in charge at each corner, exactly where the touch event took place and then relays that information to the touch-screen driver software.

So which is better ? Well, each has its own advantages and disadvantages.
Resistive touch screen can work with bare fingers, gloved fingers or stylus, as long as there is something that creates the pressure. Resistive touch screen is also much cheaper than capacitive counterpart. However it is less sensitive than capacitive touch screen and has poorer display outdoors.Resistive touch screen is now usually confined to kiosks in public places and electronics like printers which require limited touch gestures.
Capacitive is the expensive of the two. It is more sensitive and can support multi touch too. It is now dominantly used in mobile phone, tablets and other handheld devices. However it only works with bare hands and is less resistant than resistive touch screen.