wp_siteurl in config In WordPress,  WP_SITEURL  is a constant that can be defined in the  wp-config.php  file to specify the WordPress address (URL).  This constant determines the location of your WordPress core files and is used by the  site_url()  API function. Purpose of  WP_SITEURL  in  wp-config.php : Overrides database value:   When defined in  wp-config.php ,  WP_SITEURL  takes precedence over the  siteurl  value stored in the WordPress database's  wp_options  table. Reduces database calls:   Setting this constant can potentially reduce the number of database queries required to retrieve the site URL during page loads. Temporary URL changes:   It is particularly useful for temporarily changing the WordPress address, such as during site migration or troubleshooting when you cannot access the WordPress admin dashboard. Previewing on temporary domains:   Allows previewing a site on a temporary domain without altering the database, preventing redirection to the old server. How to define  WP_SITEURL : Access  wp-config.php :  Connect to your server using FTP or your hosting provider's file manager and locate the  wp-config.php  file in your WordPress installation directory. Edit the file:   Open  wp-config.php  in a plain text editor. Add the definition:   Add the following line before the line that says  /* That's all, stop editing!   Happy publishing.   */ :   Code define('WP_SITEURL', 'http://yourdomain.com');