There are several popular touchscreen devices available today that use capacitive touchscreens. This means that the screen doesn’t recognize pressure but reacts to changes in capacitance. If you’re using something other than your exposed finger you must have some conductive material for the screen to respond.
So why not just use a finger if that’s what your device (such as an iPhone or iPad) is designed for? The answer is obvious for people who use drawing applications, want to take notes, or wear long nails. Sometimes you just need more accuracy than your finger provides. Another use for a stylus is for gloved operation of your device if it happens to be cold.
There are several options for capacitive styli. Most of them are in a pen form factor with conductive foam at the tip. You can also create your own stylus if you’re so inclined. Sausages seem to work but I’d worry about the grease factor with those.
Click the following link for more information about a capacitive stylus.
