"Page Not Found" is an error message that appears when a user tries to access a webpage that no longer exists or has been moved. This can happen for various reasons, such as a broken link, a mistyped URL, or the removal of the page by the website owner. The standard error code for this issue is 404. When encountering a "Page Not Found" error, users are often presented with suggestions to navigate back to the homepage or search for other content on the site. This helps them find the information they were looking for, even if the specific page is unavailable.