A touch screen works by detecting user input through touch or gestures. There are two primary types: resistive and capacitive. Resistive touch screens consist of multiple layers that sense pressure when the outer layer is pressed. In contrast, capacitive screens use electrical properties of the human body to detect touch, allowing for multi-touch gestures. These screens convert touch input into electrical signals, which are processed by the device's operating system to perform the corresponding actions, making them suitable for user-friendly interfaces.