Try It!
To see the 404 plugin in action, just enter a filename that doesn’t exist on this site in your browser.
For example: http://www.404plugin.com/not-found
You will be served a page with a list of pages on the site containing the terms in your filename.
If no related pages are found on the site, results from around the web will be served.
This helps your site with Search Engine Optimization (SEO) by creating relevant destination pages for terms outside sites link to, or visitors seek. It also helps visitors find what they are looking for on your site, even if they mistype the web address.