This document discusses monocular depth cues, which are visual cues that allow humans to perceive depth and distance using one eye. It explains five types of monocular depth cues: superimposition, relative size, texture gradient, linear perspective, and height in the plane. For each cue, it provides a brief definition and example to illustrate how that cue provides information about an object's distance and depth. The overall document aims to help readers understand the monocular depth cues that enable 3D perception using a single eye.