Path tracing is a rendering technique used in computer graphics to simulate realistic lighting. It works by tracing the paths of rays of light as they travel through a scene, bouncing off surfaces and interacting with materials. This method captures complex effects like reflections, refractions, and shadows, making images look more lifelike. In path tracing, each ray starts from the camera and travels into the scene, gathering color and light information from the surfaces it encounters. By averaging many rays, the final image achieves a high level of realism, similar to how light behaves in the real world, making it popular in applications like film, video games, and architectural visualization.