Touch screen monitors work by using one of three systems. The systems are resistive, capacitive or surface acoustic wave. All three systems implement electrical charges and currents that detect changes that occur on the surface of the monitor.
A resistive system uses two metallic panels placed over a normal glass panel. When the monitor is in use, an electric current runs through both panels. Human touch causes changes in the electrical field through both layers of panels. These changes are calculated by the computer, and a specialized driver translates the change into a command that the operating system can execute.