光是电磁波谱中人眼可见的部分（波长范围为 380 至 780 纳米）。光的强度被感知为亮度，光谱的组成被感知为颜色。在某些应用领域，还需要添加更小波长（紫外线）和更大波长（红外线）的光。
光的物理特性可以用各种不同的模型来描述：在射线光学中，光的直线传播用 "射线 "来形象化；而在波光学中，则强调光的波的性质。这也可以解释衍射和干涉现象。最后，在量子物理学中，光被描述为量子物体（即光子）的流动。
如果光遇到物质，那么光和物质之间就会发生相互作用。光可以减速、旋转、反射、分散、吸收或折射。
本节主题
Light is the portion of the electromagnetic spectrum that is visible to the human eye (with a wavelength range of 380 to 780 nm). The intensity of the light is perceived as brightness and the composition of its spectrum as color. For some areas of application, smaller wavelengths (ultraviolet) and larger wavelengths (infrared) are added on.
The physical properties of light can be described using various different models: In ray optics, the straight-line propagation of light is visualized using "rays"; in wave optics, the emphasis is placed on the wave nature of light. This also allows diffraction and interference phenomena to be explained. Finally, in quantum physics, light is described as a flow of quantum objects, namely photons.
If light encounters matter, then interaction occurs between the light and the matter. Light can be slowed down, rotated, reflected, dispersed, absorbed or refracted.