I am a PHP developer.
Plugins & Themes
WordPress is built with the PHP programming language. All plugins are written in PHP, and themes are loaded with PHP template tags.
Although many WordPress developers rely on dozens of plugins, without PHP knowledge your website will eventually reach a stagnant point or even code conflicts.
I use a minimal number of plugins because most of the functionality many plugins can be created with code. This goes with my method of clean, well documented code with the goal of extensibility.
Built In WordPress Functions
WordPress has hundreds of built in functions that already have security and stability built in. Using these built in functions is the WordPress way, and goes a long way in keeping your website functioning correctly.
This is a very small sample of built in functions from the WordPress Developer’s Guide.