Making URLs readable and stable.
WHY IT MATTERS
Readable URLs are easier to share, better for search, and do not expose your application's internal structure.
HOW IT WORKS
The web server rewrites an incoming request internally to a different path, invisibly to the visitor. A request for /products/blue-shirt is handled by index.php with parameters.
IN WORDPRESS
Settings > Permalinks. Choosing a structure writes the necessary rules to .htaccess.
Re-saving permalinks regenerates them, which fixes 404s on every page but the homepage after a migration.
IN FRAMEWORKS
Most ship with an .htaccess routing all requests to a front controller. Ensure it transferred during deployment; its absence is a common post-migration fault.
COMMON PROBLEMS
404 on every page but the homepage: rewrite rules missing or mod_rewrite not active
Rules working locally and not on the server: different server configuration
Rules overwritten by the application, when placed inside its managed block
CHANGING URL STRUCTURE ON A LIVE SITE
Redirect the old URLs to the new ones. Otherwise every link and search result pointing at the old structure breaks.
