I intend to discuss the "behind-the-scenes" code that went into this site. For now, I can give only a very short summary. Please check back later for a more lengthy discussion.
Today's movement of web page coding is a migration from html to xml (or an xml-based html). The redesign of this site (redesign begun August 2001) takes a serious step toward xml (or xhtml).
The beauty of xml is that is it allows one to separate page content from the code that formats that content and from code that provides special behavior. For example, all article pages will contain mostly the text to be displayed. The tags will classify blocks of text as "title," "author," "date-posted," "paragraph," "link," etc. Afterall, that's all a content page should have to do!
The content page links in a "style" page (.css extention). This style page directs how each of these blocks of text are to be formatted (color/size of font, borders, margins, etc.). Because all my article pages reference the same style page, with one format adjustment on that one style sheet, all article pages will be formatted with the change.
Special behavior is isolated to javascript pages (.js extention). For instance, the species pages use a menu that enables blocks of text to appear and disappear. This menu behavior is stored in a js file that each species page references. If I want to change the behavior in someway, I just change it in the "js" page for species and all species pages will behave the new way.
So if you view the source of the redesigned pages, you will see very "clean" code with mostly content. Common style and common behavior are each written just once and stored in a commonly accessed file. To a coder, this is beauty!
One more point... By relying on "style sheets" to format my pages, I have a high amount of control. Whereas pages used to be based on tables with "tr" and "td" tags, styles allows me to format without this messy code. Not only do my pages avoid the clutter, but changes are a lot easier.
Actually, those people who form the HTML rules have deprecated (declared out-dated and destined to be unsupported in the future) several html tags that are used today. This includes even frames !!! All of these things can be supported with styles and newer html tags. (But since some browsers fail completely when encountering the new "iframe" tag, I'm still relying on the traditional "frames.")
So I suggest that anyone who writes web code start looking at the new rules. Someday the pages you write the old way will no longer be readable -- when tomorrow's browsers become common place.