WordPress Plugins in a Nutshell
Understanding how WordPress plugins work will be beneficial if you are interested in developing your own or extending existing ones to suit your needs.
What is a WordPress plugin?
A WordPress plugin alters or extends core functionalities that are built-in to WordPress. In other words, plugins are files that are installed, activated or sometimes created in a WordPress site to add a feature, or set of features and it can range from a simple calendar widget to a full-featured e-commerce system.
When are WordPress plugins loaded?
WordPress plugins are loaded early when you visit a page in a WordPress site, WordPress will go through the following standard loading process:
- First it will load the
wp-config.phpfile located in the root directory.
- Second, it will load the
functions.phpfile under the
- Third, it will load all the plugins that are installed and activated.
- Fourth, it will load the pluggable functions. These functions override specific core functions in a plugin. An example would be the
wp_mailfunction. You can use this function in your plugin to send email using SMTP rather than the default
pluggable.phpcore WordPress file under the
- Fifth, it will load the translations that are done through internationalization and localization.
- Sixth, it will load the theme that is currently active.
- Lastly, it will load the page content.
WordPress Plugin Directories
WordPress features two plugin directories. The primary directory for plugins is located under
wp-content/plugins. The second, lesser known plugin directory is located under
wp-content/mu-plugins. MU which stands for “Must-Use” is not created by WordPress, it must be manually created to be used.
The plugins under the
mu-plugins directory doesn’t have an activate/deactivate feature and will always be executed globally. The only way to deactivate one is by deleting the file completely with conviction…
WordPress Plugin Types and Statuses
WordPress features a few types and statuses for plugins:
- Active – A status that indicates that a plugin is active and running in WordPress.
- Inactive – A status that indicates that a plugin is installed but not active and no code from the plugin are being executed.
- Must Use – These are plugins that are created manually in the
wp-content/mu-pluginsdirectory and are loaded site-wide automatically.
- Drop-ins – These plugins replaces core WordPress functionalities, they are a specifically named PHP files located in the wp-content directory. Here’s some drop-ins that are available:
Where to download WordPress plugins?
WordPress plugins can be downloaded (either paid or free) from a variety of sources like CodeCanyon and the Official WordPress Plugin Directory. All the plugins available in the plugin directory are 100% GPL and free to use for personal or commercial purposes.
Next Post: Action Hooks in WordPress
This is part 1 of the WordPress Plugin Development series.