What is 404 Plugin?
This simple plugin will give you a customized, smart ‘Page Not Found(404)’ error message. It will automatically display links to relevant pages on your site, based on the words in the URL that was not found.
Installing this plugin is beneficial for SEO (Search Engine Optimization) because it will make your site appear to have relevant pages even for those URLs that you actually don’t have. This can increase your search engine ranking.