A stereoscope is an optical device that allows users to view two slightly different images of the same scene, creating a three-dimensional effect. This device typically consists of two lenses and a viewing chamber, where each eye sees a different image, mimicking how human vision works. Stereoscopes were popular in the 19th century for viewing photographs and illustrations. The concept of stereoscopy is based on the principle of binocular vision, which is how our eyes perceive depth. The invention of the stereoscope is often attributed to Sir Charles Wheatstone, who demonstrated the effect in 1838. Today, similar technology is used in virtual reality and 3D movies.