Auto white balance
Also known as: AWB, automatic white balance
Leaving the camera to guess the colour of the light and correct for it continuously, which is convenient and drifts mid-shot.
Updated
What it means
Automatic balance analyses the picture and then looks for something in it that ought to be neutral. The guess is usually close, and it gets made again every few frames, which is where the trouble actually starts.
It is the automatic mode of White balance rather than a different setting. One is the control itself; this is simply what happens when nobody has set it at all.
The failure is movement rather than error. A single wrong value is one correction to make in post, where a value that changed three times during one run is three separate ones.
How it works in practice
A fixed value is the fix. Choosing a Kelvin figure for the conditions and then locking it means every clip of the session matches, which is worth more than any individual clip being perfect.
Two values cover most days. Something for sunlight and something for shade, chosen once and left alone, handles a session better than a camera guessing continuously does.
Where it has to stay automatic, consistency comes later. Color matching can reconcile clips that disagree, as long as the disagreement is between clips rather than inside any one of them.
What to watch out for
Mid-clip drift is the expensive one. A pass from sunlight into forest shifts colour while the camera is recording, and fixing that needs Keyframe animation rather than a single correction.
Water and snow confuse it very badly indeed. A frame filled with one colour gives it nothing neutral to find, so it corrects toward the dominant tone and makes the whole frame worse.
Underwater it is hopeless. Depth removes red entirely, and an automatic setting chases a balance that does not exist, which is why a Red filter belongs on the housing instead.
How RawClip handles it
Clips that disagree about colour are brought into agreement while the sequence is assembled, which handles a card shot on automatic. A clip whose colour shifts part way through is a harder case, and a fixed value chosen at capture avoids the whole problem before it starts.