The HTTP code associated with a 404 page is "404 Not Found", which means that the server cannot find the requested resource. 404 pages are often customized to match the appearance of the website and may include detailed error messages, suggestions to help users find what they are looking for, or links to other pages on the site. 404 pages can be created to inform users that the page they are looking for is not available and help them find what they are looking for.