WordPress believes in keeping it simple, and a lot of thought goes into including new functionality as a part of the "core" WordPress code, in order to keep WordPress fast and lightweight. Still, users often find the need to graft additional functionality onto WordPress to meet their needs. This section of the Codex offers guidelines and references for anyone wishing to modify WordPress.
In the following articles you may encounter programming terms that are not explained in the usual level of detail required for understanding by non-programmers.
Although the alteration of the downloadable files for WordPress is limited to a few distinct programmers, every WordPress user has the ability to affect change in the core WordPress code, making WordPress highly customizable.