Each time a page on your site does not load, an error message will be displayed to the visitor. As there are different errors, there are different pages which will display, but what is common for all of them is that they're generic and in all probability shall have absolutely nothing in common with the design of your site, which could be frustrating for any site visitor. This is the reason why hosting providers have introduced a feature referred to as Custom Error Pages. For a number of different errors, visitors will see your custom content, which may be informative or humorous, in accordance with your choice, and that will match the style and design of your website, so the pages shall not look like they are not part of your website at all. You may use this option for numerous errors - 400 (Bad request), 401 (Unauthorized), 403 (Forbidden) and 404 (File not Found).