What are the most common causes of a 403 Forbidden error in a WordPress website?

The most common causes for a 403 Forbidden error in WordPress include incorrect file and directory permissions (e.g., WordPress files or folders are not readable/writable by the server), a corrupted or misconfigured .htaccess file, security plugins (like Wordfence or Sucuri) blocking access due to perceived threats or rule violations, IP address restrictions, or server-level firewall rules.