Whenever a page on your website doesn't load, an error message shall be shown to the visitor. Because there are different errors, there are different pages that'll show up, but what is standard for all of them is that they are generic and in all probability will have nothing that resembles the layout of your Internet site, which may be annoying for any site visitor. That is the main reason why website hosting service providers have introduced a feature called Custom Error Pages. For a range of different errors, website visitors will see your customized content, which may be informative or funny, based on your personal preference, and which will match the overall layout of your Internet site, so the pages will not seem like they aren't part of your website at all. You could use this option for a number of errors - 400 (Bad request), 401 (Unauthorized), 403 (Forbidden) and 404 (File not Found).