404 page is a default error page that pops up when a user navigates to an internet address that does not exist. Custom 404 pages are usually designed in such a way that it is different from any other webpage and includes subtle, or not so subtle, marketing messages. This may be because the business wants to show off its design skills and/or emphasize the fact that they offer something unique and worth visiting. Custom 404 pages may also offer links to other content on the website or even provide information about how to connect with customer service.