A graphics tablet (or digitizing tablet) is a computer peripheral device that
allows for a relatively simple method of inputting hand-drawn graphics or art
into a computer in real time. They typically consist of a large flat surface for
drawing on, and an attached "stylus" for drawing on the surface, originally as a
part of the electronics, but later simply to provide an accurate but smooth
"point".
The final evolution in the graphics tablet is the pressure-sensitive pad. In
these devices the X and Y grids are separated by a thin insulator, and when the
pad is pressed the two wires come into contact at the pressure point. This
allows current to flow into one X and out of one Y wire (or vice-versa) thereby
locating the stylus. These systems tend to be lower resolution, with increases
in resolution requiring more wiring which drives up the cost. At some point
there is a sweet spot where the magnetic systems become more reasonable, as they
can interpolate between wires to provide higher resolution without more wiring.