What causes random colored-light circles in various photos?

[james.goetz]

I've seen photos with apparently random colored-light circles.
What causes that?
And what can prevent that?

 

[DexGtr]

are you talking about flare?

 

[Big Mike]

Sounds like lens flare. It's caused by light bouncing around inside the lens & camera.

 

[Idaho21]

It is either lens flare or caused by a UV filter. If you aren't using a UV filter, it would be lens flare.

 

[james.goetz]

Thank you for teaching me that I asked about lens flare.