Depth estimation is the process of determining the distance of objects from a viewpoint, often used in computer vision and robotics. It helps machines understand the 3D structure of their environment by analyzing images or video feeds. Techniques for depth estimation include stereo vision, where two cameras capture images from slightly different angles, and monocular depth estimation, which uses a single camera and machine learning algorithms. Accurate depth estimation is crucial for applications like autonomous vehicles, augmented reality, and 3D modeling. By knowing how far away objects are, systems can make better decisions, navigate safely, and create realistic virtual experiences.