404 Not Found
The 404 or Not Found error message (HTTP 404 Not Found,404 File or Directory Not Found) is a standard response code indicating that the Server cannot find the URL requested but the client was actually able to communicate with a given server or it was configured not to fulfill the request.
404 Not Found error messages can appear in any browser or any operating system. Most 404 Not Found errors display inside the Internet browser window just as web pages do. 404 Not Found error messages are frequently customized by the websites.
In addition, Error 404 is usually, a client-side error, implying that the error is the client mistake, either because the URL was typed incorrectly or the page has been moved or removed from the website and the client should have known. Another possibility is if a website has moved a page or resource but did so without redirecting the old URL to the new one (usually by using redirect 301). When that happens, you’ll receive a 404 error instead of being automatically routed to the new page.