WordPress plugins is what gives WordPress the extra power and enables you to extend the functionality of WordPress so that you can do more or less anything you like. At the time of writing this post almost 14 thousand plugins exists in WordPress plugin directory.
Most users of WordPress think that there is only one type of plugin. However, there is actually three types of plugins that you can use.
This is the plugins that you normally download from the plugin directory at WordPress.org. These plugins are located in the wp-content/plugins directory.
These plugins can have the following statuses.
- Active – The plugin is active and plugin code will be executed
- Inactive- The plugin is installed but inactive and no code is executed
- Upgrade Available – A new version of the plugin is available
The must-use plugins are very similar to normal plugins. The main difference is that they are placed in the wp-content/mu-plugins directory and can not be located in a subfolder.
The mu-plugins directory is created by default if you install WordPress Multisite (WordPress MS) but you can use it in the normal installation of WordPress if you manually create the mu-plugins directory.
These plugins are activated by default and the only way to deactivate them is to remove them from the mu-plugins directory. Must-use plugins are listed under “Must-use” in the plugins page.
Drop-ins are plugins that can replace core functionality of WordPress. These kind of plugins are placed in the wp-content directory and must be named in a certain way for WordPress to be able to auto-load them. Drop-ins plugins are listed under “Drop-ins” in the plugins page and is activated by default. Remove them from this directory if you want to deactivate them.
Drop-ins available in WordPress and WordPress MS
- advanced-cache.php – Advanced caching plugin
- db.php – Custom database class
- db-error.php – Custom database error message
- install.php – Custom installation script
- maintenance.php – Custom maintenance message
- object-cache.php – External object cache
WordPress Multisite specific drop-ins
- sunrise.php – Advanced domain mapping
- blog-deleted.php – Custom blog deleted message
- blog-inactive.php – Custom blog inactive message
- blog-suspended.php – Custom blog suspended message