When a user requests a non-existent page on your site, the web server gives a 404 error and displays an abnormal page.
Having a customized page 404 in your design is essential. This offers you the following benefits:
- If your page 404 has links to other pages on your site, then the user will probably click on them, rather than close the site.
- If you place some funny pictures on this page, the negative experience of the user will be reduced.
- Standard error pages 404 can confuse and frustrate the user.
- Search engines rank sites with custom page 404 better.