WHAT’S IN THIS CHAPTER?
To understand how to extend WordPress properly, you must first learn how the core of WordPress functions. This will help you learn what tools are available in the WordPress core to make your life easier. WordPress handles most of the tedious coding and logic problems for you.
The WordPress core is the best resource for learning how WordPress works. The beauty of open source software is you have all of the code at your disposal. If you are ever unsure how a certain aspect of WordPress functions, just start digging into the code! The answers are all there; it’s just a matter of finding and understanding them.
The WordPress core is powered by a set of files that are part of the original WordPress software download. These are required “core” files that WordPress needs to function properly. The core files are expected to change only when you upgrade WordPress to a newer version.
The core does not include your custom files for plugins, themes, database settings, the .htaccess file, and so on. The core also does not include any media you have uploaded to WordPress. Basically, any files added to WordPress after installation are considered outside of the core.