Capacitance is a property of an electrical system that lets it store charge in an electric field. In simple terms, two conductors separated by an insulator can hold energy, and that stored charge changes when the surrounding conditions change. A human finger near a sensor changes the electrical field and increases the measured capacitance, which is why touch controls can detect a press without a moving button.
In cyber security, capacitance matters because it is the sensing principle behind many touch panels, capacitive keypads, and some tamper-detection circuits. Attackers can abuse that sensitivity with conductive overlays, false-touch injection, moisture, or electromagnetic interference to trigger unwanted input or cause denial of service. Defenders reduce that risk with shielding, filtering, threshold tuning, baseline calibration, and sensor designs that ignore noise while still recognizing real touch.