How do touchscreens work?

Most smartphones and tablets use capacitive touchscreens, which work by sensing the electrical properties of your finger. The screen has a transparent grid of conductive material holding a small electrical charge. Because the human body conducts electricity, touching the screen draws a tiny amount of charge from the point of contact, and sensors detect exactly where that change happened. This is why capacitive screens usually do not respond to a gloved finger or an ordinary stylus. Older resistive touchscreens work differently, registering a touch when pressure pushes two flexible layers together, which is why they respond to any object but feel less sensitive.