This lecture introduces the concept of ray tracing in computer graphics, focusing on the basics of the ray tracing algorithm. The instructor explains the process of generating primary rays, computing intersections with objects in the scene, and evaluating lighting models for diffuse and specular surfaces. The lecture covers the classification of light paths in ray tracing, including diffuse, specular, and glossy reflections. The instructor also discusses the limitations of the basic recursive ray tracer, such as the inability to handle multiple diffuse bounces and caustics. Through examples and illustrations, students learn how ray tracing can create realistic images by simulating light interactions in a scene.