Light Flare / Lens Flares Defined

https://en.wikipedia.org/wiki/Lens_flare

According Wikipedia "Lens Flares" aka Light Flares" is defined as:

"Lens flare refers to a phenomenon wherein light is scattered or flared in a lens system, often in response to a bright light, producing an undesirable effect on the image. This happens through unintentional image formation mechanisms, such as internal reflection and scattering from material imperfections in the lens. Lenses with large numbers of elements such as zooms tend to exhibit greater lens flare, as they contain multiple surfaces at which unwanted internal scattering occurs. These mechanisms differ from the intended image formation mechanism, which depends on rays from the refraction of the image itself. Using this principle, lens flares can be theoretically seen if you are wearing glasses."

Images and definition credit Wikipedia

Light coming from a narrow angle may be "trapped" and reflected between the surfaces of the lens elements.

Examples from Wikipedia

Lens flare on Borobudur stairs to enhance the sense of ascending