Light is a form of electromagnetic radiation that is visible to the human eye. It travels in waves and can behave both as a wave and as a particle, a concept known as wave-particle duality. Light can be reflected, refracted, and absorbed by different materials, which affects how we perceive colors and brightness. The speed of light in a vacuum is approximately 299,792 kilometers per second (or about 186,282 miles per second). When light passes through different media, such as air or water, it slows down, which can cause bending, known as refraction. This property is essential in lenses used in glasses and cameras.