Each time a page on your site doesn't load, an error message shall be shown to the website visitor. Since there are different errors, there are different pages that will display, but what is common for all of them is that they are generic and probably shall have practically nothing in common with the design of your Internet site, which could be irritating for any visitor. This is the reason why hosting providers have introduced a feature called Custom Error Pages. For a number of different errors, site visitors shall see your custom content, which may be informative or amusing, in accordance with your choice, and which shall match the layout of your website, so the pages will not look 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).