The easiest way to understand what WordPress does, and how it does it, is to dig into the following analogy: WordPress is a factory that makes webpages.
The WordPress factory's raw materials are its posts, and its warehouse (where it stores its raw materials) is the MySQL database.
The factory's assembly lines are the various PHP template files of the WordPress theme.
The factory can call on specialized outside contractors for specific jobs; these are WordPress plugins.
The finished product is the full HTML markup necessary to display a webpage; the factory ships this product to the requesting user's browser on every page load.
Much of this book is very specific—at the level of individual APIs and functions—but you should first have an overall, intuitive picture of how WordPress works.
This chapter introduces the most helpful analogy for understanding WordPress's overall functioning: WordPress is a factory that builds webpages. If you underst...