Active shutter glasses are a type of eyewear used in 3D displays to create the illusion of depth. They work by rapidly alternating between blocking the left and right lenses in sync with the images displayed on a screen, such as a 3D television or projector. This synchronization allows each eye to see a different image, enhancing the 3D effect. These glasses are powered by batteries and often use infrared signals to communicate with the display device. Unlike passive glasses, which rely on polarized lenses, active shutter glasses provide a more dynamic and clearer 3D experience, making them popular for home theaters and gaming.