Function: Load the database class file and instantiate the `$wpdb` global.

Function: Set the database table prefix and the format specifiers for database table columns.

Function: Toggle `$_wp_using_ext_object_cache` on and off without directly touching global.

Function: Start the WordPress object cache.

Function: Redirect to the installer if WordPress is not installed.

Function: Retrieve an array of must-use plugin files.

Function: Fix `$_SERVER` variables for various setups.

Function: Checks for the required PHP version, and the mysqli extension or a database drop-in.

Function: Don’t load all of WordPress when handling a favicon.ico request.

Function: Die with a maintenance message when conditions are met.