My Thoughts on Chapters 12 and 13

For Chapter 12 I don't really understand the difference between <div> id's and classes, but I do understand a little bit about layouts. For Chapter 13 I don't really understand how you can float something within a float, but I do understand multiple column layouts. I'm sure that with more practice on the tutorials and implementing these techniques in my personal website I will learn more about these different techniques and how they change the styling of my site.