How does a touchscreen work?
A touchscreen works by turning a touch on the display into a position the device can understand. Resistive screens do this by sensing pressure: your finger or stylus pushes layers together at the touch point. Capacitive screens do it by sensing a change in an electrical field when conductive skin, or a suitable stylus, comes near the surface. The device’s touch controller reads that signal, works out where it happened, and passes the result to the software as a tap, drag, press, or gesture.
Resistive touchscreens
A resistive touchscreen is built from flexible conductive layers with a small space between them. When you press the surface, the upper layer bends until it meets the lower layer. That contact changes the electrical signal at that spot, and the controller translates the change into screen coordinates.
The useful thing about resistive touch is that it responds to pressure, not to the electrical properties of your finger. A gloved hand, a fingernail, or a simple plastic stylus can work. That makes resistive screens practical in places where users may wear gloves, where the screen may need firm input, or where simple tapping matters more than gesture control.
The trade-off is feel. Because the screen needs pressure, it can seem less immediate than a capacitive screen. The extra layers can also affect how clear the display looks. Resistive touch is good at registering a deliberate press, but it is not the natural fit for rich multi-touch gestures.
Capacitive touchscreens
A capacitive touchscreen uses a transparent conductive layer beneath the glass. The screen maintains an electrical field across that layer. When your finger touches or comes close to the surface, it changes that field in a local area because your body conducts electricity. The controller detects the change and calculates the touch position.
This is why most phone and tablet screens respond to a light touch rather than a firm push. The glass does not need to flex in the same way. It also explains why ordinary gloves often do not work unless they include conductive material, and why a stylus for a capacitive screen needs the right kind of tip.
Capacitive touchscreens usually feel faster and smoother because they can detect small changes across the surface. They also suit glass-fronted devices, where clarity and a light touch matter.
Single-touch and multi-touch
Single-touch means the screen follows a lone contact point at a time. That is enough for simple actions such as tapping a button, selecting an item, or dragging something across the screen. If another finger touches the display at the same time, a single-touch system cannot reliably treat both contacts as separate inputs.
Multi-touch means the screen can track separate contact points together. This lets software read the relationship between those contacts, not just their individual positions. A pinch-to-zoom gesture works because the device sees the contacts move closer together or farther apart. A rotation gesture works because it sees their angle change.
The difference is not just technical. Single-touch treats the screen like a set of buttons and sliders. Multi-touch lets the screen behave more like a surface you can manipulate directly, which is why modern touch interfaces feel natural for maps, photos, drawing, typing, and games.