A capacitive sensor is a type of electronic device that detects changes in capacitance, which is the ability of a system to store an electric charge. These sensors work by measuring the electrical field around them and can detect the presence of objects, typically conductive materials like the human body. They are commonly used in touchscreens, where a user's finger alters the electric field, allowing the device to register a touch. Capacitive sensors are also found in various applications, including smartphones, home appliances, and automated systems. They are favored for their sensitivity and ability to work without direct contact, making them ideal for modern technology that requires user interaction without physical buttons.