I get it all the time on my photographs. Can someone explain what it is exactly and how to avoid it?

Probably CA does it happen at full telephoto mostly? What kind of camera and lens?
CA - chromatic Arborhition ( not sure on the spelling)

CA = Chromatic Aberration

Chromatic aberration - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Chromatic_aberration)

Could also be in-camera sharpening and/or compression artifacts. Kyle, can you post a picture that shows it?

Pixel bleed - where there is too much light compared to surrounding pixels and (electronically) some spillage occurs.

Or it could be a chromatic aberration issue as per above.

Andrew

PS. Really could do with a still image to view.

Or maybe there was a bluebird streaking through the frame:<)

Anyhow, as others are saying, could be a lot of things and without seeing it it's awfully hard to know what is causing it.

. . . like even stripe filter color seperation stuff to achieve color from a single chip
more cheap tricks that i dont totally understand.

Did your camera cost more or less than $29.95? ;-)