The Nature of Light

The very nature of light has been the subject of philosophical consideration since antiquity. As a physical entity, many people have suggested that light has a corpuscular nature, formed of particles, while others have proposed a wave nature instead. Physical entities can be classified as either waves or particles. Waves spread out in space (diffraction), can pass through obstacles, and can be added to other waves (superposition). Particles, on the other hand, move in straight lines due to their inertia unless a force is exerted upon them. If they encounter an obstacle, they simply reverse direction. Light has both properties at the same time! So the questions to ask are: How is light classified? What is light, which we cannot see, but thanks to it, we see?