Permalinks are the URL format for your content. Set this once, early — changing it later breaks every existing link unless you set up redirects.
Setting it
- Go to Settings → Permalinks.
- Select Post name.
- Click Save Changes.
This produces yourdomain.com/about-us/ rather than yourdomain.com/?p=42 — clearer for visitors and better for search engines.
When to use something else
News sites that publish many articles a day sometimes prefer a date-based structure. For everything else, Post name is the right default.
If you must change it on an established site
Install the Redirection plugin first and set up 301 redirects from old URLs to new ones, otherwise every indexed page and every shared link will 404.
Re-saving to fix problems
Clicking Save on this screen regenerates .htaccess, which is the standard fix for site-wide 404 errors after a migration or restore.
