Sensors are devices that detect and respond to physical stimuli, converting them into signals that can be measured or recorded. Common types include temperature sensors, which measure heat levels; pressure sensors, which gauge force applied to an area; and proximity sensors, which detect the presence of nearby objects without physical contact. Another category includes light sensors, which respond to changes in illumination, and motion sensors, which detect movement. Chemical sensors analyze the presence of specific substances, while ultrasonic sensors use sound waves to measure distance. Each type serves unique applications across various fields, including automation, healthcare, and environmental monitoring.