Motion-activated lights are lighting systems that turn on automatically when they detect movement within a certain range. These lights use sensors, typically PIR (Passive Infrared) sensors, to sense changes in heat and movement. They are commonly used for security purposes, illuminating areas when someone approaches, which can deter intruders. These lights are often installed outdoors, such as in driveways or gardens, but can also be used indoors, like in hallways or bathrooms. They help save energy by only turning on when needed, making them an efficient choice for both residential and commercial spaces.