Stereoscopy is a technique used to create the illusion of depth in images. It involves presenting two slightly different perspectives of the same scene, one for each eye. This mimics how human vision works, allowing the brain to perceive three-dimensional depth from two-dimensional images. The most common form of stereoscopy is through 3D glasses, which filter the images so each eye sees only its designated perspective. This technology is widely used in cinema, virtual reality, and photography to enhance the viewing experience, making it more immersive and realistic.