A "404 page" is an error message displayed when a user tries to access a webpage that cannot be found on a website. This can happen for various reasons, such as the page being deleted, the URL being typed incorrectly, or the link being broken. The term "404" refers to the HTTP status code that indicates this specific error. Typically, a 404 page will inform users that the requested page is unavailable and may offer suggestions for navigating the site, such as links to the homepage or a search bar. Many websites customize their 404 pages to make them more user-friendly or entertaining, helping to retain visitors even when they encounter an error.