Custom 404 pages that display an error message of “404 Not Found – You Have Reached This Page in Error” can be valuable. They provide a convenience for users who have made typographical errors, and they also inform users who have accidentally requested non-existent pages from your web site.
These “404 Not Found” pages can also provide “home” links and, if desired, suggestions from Google (if you use Google’s site-wide keyword search option) on possible misspellings the user might have entered, along with the familiar “do you mean …….?” prompts.
Having these pages display your logo and web site branding also assures the user that they still have easy access to your web site, and also increases the chances that the user will indeed return to your web site before going elsewhere.
Customizing your “404 Not Found” pages is also recommended by Google. For more information regarding customizing your “404″ pages, or for further information about organic search engine optimization, see Google’s Search Engine Optimization Starter Guide.
For more information on search engine optimization, see Organic SEO.


