But it's also a universal format for displaying information globally. By understanding those limitations and capabilities and exploiting both is the key to becoming a good Web designer. Your chapter on Speed was quite interesting. Well, first there is the user experience. No matter how well designed and usable your site may be, if nobody waits around for it to download, it will be wasted.
Speed is the most important factor in the success of any site.
Make a slow site, and people won't use it. It's as simple as that. But there is a purely financial aspect to it, as well. I was once talking to a CTO of a very large website who explained that they had done a cost analysis of their bandwidth. They found that with the amount of traffic they had, they were spending 16 cents per month per character in their HTML source code.