Touch Without Buttons

Your touchscreen works on capacitance. The surface holds a grid of transparent electrodes carrying a tiny charge. When your finger approaches, your body — mostly conductive water and salt — distorts the electric field at that point.

This is why:

• Gloves block your touch, because fabric insulates your skin's conductivity
• Styluses need a conductive tip to register
• Water droplets cause phantom touches, because they conduct too

You are not pressing a button. You are disturbing an electric field with your body.