Light is a form of electromagnetic radiation that is visible to the human eye, typically ranging in wavelength from about 380 to 750 nanometers. It is a fundamental aspect of the universe, enabling vision and playing a crucial role in various natural processes. Light behaves both as a wave and a particle, a duality that is central to quantum mechanics. As a wave, it exhibits properties such as interference, diffraction, and polarization. As a particle, it is composed of photons, which are massless packets of energy that travel at the speed of light (approximately 299,792 kilometers per second in a vacuum).

Light is essential for life on Earth, driving photosynthesis in plants, which forms the basis of the food chain. It also influences circadian rhythms in animals, including humans, regulating sleep and wake cycles. The study of light, known as optics, has led to numerous technological advancements, from microscopes and telescopes to lasers and fiber optics. Light's interaction with matter can result in phenomena such as reflection, refraction, and absorption, which are harnessed in various applications, from photography to solar energy. In essence, light is not only a physical phenomenon but also a vital component of our understanding of the universe and our daily lives.