3D glasses are special eyewear designed to create the illusion of depth in images, making them appear three-dimensional. They work by presenting slightly different images to each eye, which the brain then combines to perceive depth. These glasses are commonly used in 3D movies, virtual reality, and video games. There are different types of 3D glasses, including anaglyph glasses, which use colored lenses, and polarized glasses, which have different light filters. Some modern displays, like 3D TVs, may require active shutter glasses that sync with the screen. Overall, 3D glasses enhance visual experiences by adding depth to images.