Geometric optics is the branch of optics that studies the behavior of light as it travels in straight lines. It focuses on how light interacts with various surfaces, such as mirrors and lenses, to form images. This field uses concepts like reflection and refraction to explain how light changes direction when it encounters different materials. In geometric optics, light is often modeled as rays, which simplifies the analysis of optical systems. Key principles include the laws of reflection, which describe how light bounces off surfaces, and Snell's law, which explains how light bends when passing through materials like glass or water.