“Resistive” touchscreens connect a circuit within the screen when there is pressure on it.
“Capacitive” touchscreens use the fact that the body is an electrical conductor (so you can’t use these with gloves on!).
“Surface acoustic wave” touchscreens send tiny waves over the screen that your finger interrupts (so dirt on the screen can make a big difference to these).
“Infrared” touchscreens send beams of light across the screen that are interrupted by your finger.
“Optical imaging” touchscreens use a set of cameras around the screen to look for the shadow of your finger.
The most common types used in mobile phones and other similar devices are “Resistive” touchscreens (used my most manufacturers) and “Capacitive” touchscreens (used by Apple and a few others). There are pro’s and con’s to to each type of technology.
Because resistive touchscreens rely on pressure, you can operate them with just about anything. Capacitive screens need a special stylus that is conductive in the same way as a finger.
As the Nintendo DS has a resistive touchscreen you can use pretty much anything as a stylus!
Pros and Cons
“Resistive” touchscreens are more accurate but you have to PUSH !
“Capacitive” touchscreens are easier to use “with a swish of your hand” but your finger has to TOUCH it, you can’t use gloves !! and it doesn’t work when your fingers are cold !!