White Balance just refers to the the color balance on some form of digital camera. There is white balance in both still photography and motion.
You know how some photographs appear blueish or too yellow? This is often just a case of the white balance being off.
Cameras don't work like human brains. The human brain knows that a white piece of paper is a white piece of paper regardless of whether or not you're looking at it under sunlight or a candle light.
Cameras are kind of dumb so they don't know the white piece of paper is white so if you don't set your white balance it may think the paper under candle light is actually yellow.
So, what to do? In simple terms all you need to know about white balance is that it's just best to manually set your white balance to match your light source.
So if you're shooting in daylight set your white balance to daylight. If you're shooting in a tungsten lights use tungsten. It's really quite simple. There is much more to this topic but this is really enough for the basics.
The key is to always set your white balance to match your light source if you want the color in your photographs to be as accurate as possible.
The main thing to remember here is that you want to shoot in raw and always set your white balance manually.
One of the best things about shooting raw is that you can always fine tune your white balance in post if you don't get it exactly right.
Here is an example table of the white balance settings available on the Canon 5D MK III:
Here is an example table of the white balance settings available on the Nikon D810:
There is much more to this topic but the details can get pretty boring. I'd much rather you be out shooting than reading this!
(Remember, you should totally break the rules in photography once you've understood them and mastered them. In other words, white balance can become a creative tool as well.)
Here is is a video on this subject:
Video by SLRLounge