Ray of light | lightcolourvision.org

A ray of light (light ray or just ray) is a common term when talking about optics and electromagnetism.

A ray of light is a way of imagining, conceptualising and representing the way light moves.
The idea of a ray of light is rooted in the observation that light travels in straight lines until it meets an obstacle.
It is common sense to think of a narrow beam of light as being composed of parallel arrows or a bundle of rays.
The bundle of rays can then be used to trace what happens when light strikes a complex object such as a lens or convex mirror.
Single rays are often used to plot the path of a specific wavelength of light and compare it with the path of others.

The idea that light is made up of rays is so commonplace when describing and explaining electromagnetic radiation (light) that it is easily taken for granted.
The idea of light rays is useful when trying to model things like the way light and raindrops produce the rainbow effects seen by an observer.
Light rays don’t exist in the sense that the term accurately describes a physical property of light. More accurate descriptions use terms like photons or waves.
Modelling light as rays is a way to discuss and represent the path of light through different media in a simple and easily understandable way.
When light rays are drawn in a ray-tracing diagram they are represented as straight lines connected at angles to illustrate how light moves and what happens when it encounters different situations and conditions.
More accurate descriptions of light use terms such as photons or electromagnetic waves.