Differences between different video codecs

I use DVDFab, and when backing up DVDs to video files, I can choose between mp4, avi, divx, etc. Where can I find out the difference between these different codecs? When should I choose one if I’m concerned with size or another for quality?

Thanks,
Richard

This may help some…

Thanks! That was very helpful. So there is a container format, and the container holds the video and audio streams, sort of like a zip, rar, or 7z file holds different files.