A 404 page, commonly known as an error page or a Page Not Found page, refers to the webpage that is displayed to a user when they attempt to navigate to a URL that does not exist on the server. This can occur for various reasons, such as when a user clicks on a broken link, types a web address incorrectly, or tries to access a page that has been deleted or moved without proper redirection. The 404 error is a standard HTTP response code indicating that while the server itself is reachable, the specific page the user is looking for cannot be found. An effective 404 page is designed to be helpful and guide users back to the main content of the website, often featuring links to the homepage, search functions, or popular content. It may also include creative or humorous elements to engage users and alleviate any frustration caused by the error. The goal is to retain the user on the website, reducing bounce rates and potentially improving the overall user experience.