Is there a top-down documentation for WordPress?

This may sound like a silly question, but is there any technical top-down documentation that explains how WordPress works?

There’s a lot of “How to…” style documentation, i.e. explaining how to get a certain thing (install, write a theme,…) done, but I have trouble finding any documentation that provides the bigger picture, explaining how WordPress interacts with the web server, what major components/concepts exist, how they are organized in the install and how they work together to create the delivered web pages.

I guess, if I follow enough links on Plugins, Themes, Templates, … I’ll eventually get a (hopefully) fairly complete picture, but I’d much prefer starting with high level documentation and then drill down in areas that are immediately relevant to me.

WordPress is very… utilitarian I suppose. People tend to use and know as much as they need to get things done. Curiously that tends to exclude the low level core load process.

It doesn’t help the situation that (unlike modern frameworks) WordPress doesn’t use a complete routing logic for everything. Front-end is governed by rewrite/permalinks, while back end is a spaghetti of different non-virtual endpoints.

The closest I had come to mapping it out myself is my core load graphic.

But overall there are so many things going on, that summarizing it completely is rather futile. You just live and learn (if you choose to :).