In computing, a stylus is an instrument shaped like a pen, designed to be used with graphics tablets or devices that use touch screen input. It is used to write or draw on a screen, similar to how you would on a sheet of paper. Unlike a pen, styluses have a plastic or felt tip depending on its purpose and functionality. The picture shows the Palm Z22 stylus.
Which devices use a stylus?
Originally, the stylus was not commonly found or used with devices other than graphics tablets and PDAs. However, with the rising popularity of touch screens on mobile devices, many individuals like using a stylus instead of their finger. The reasoning varies, but it's usually for more accurate navigation and keeps oils from their fingers from getting on the device's screen.
What is the difference between passive and active styluses?
A stylus can come in one of two forms: passive (also known as a capacitive stylus) or active (also known as an active stylus or active pen). A passive stylus is not different than using your finger as far as the device is concerned. An active stylus (such as the one used with the Microsoft Surface) has an electronic component that interfaces with the device's touch screen controller. They have a few distinct advantages: more accurate and finer lines, different levels of pressure sensitivity, and the ability to ignore input from your hand resting on the screen. The last feature is referred to as palm rejection.
How is a stylus an input device?
Before the touch screens we know today, the stylus was used to input data into small palmtop devices. For example, the Palm Pilot used the stylus to write symbols known as graffiti to input letters into the device.
Today, a stylus is still considered an input device because it can point to and open or manipulate objects on a screen, like a computer mouse.