Capacitive sensors are devices that detect changes in capacitance, which is the ability of a system to store an electric charge. They consist of two conductive plates separated by an insulating material. When an object, such as a finger, comes close to the sensor, it alters the electric field between the plates, allowing the sensor to detect the presence or movement of the object. These sensors are commonly used in various applications, including touchscreens in smartphones, tablets, and home appliances. They are favored for their sensitivity and ability to work through non-conductive materials, making them versatile for different environments.