A Hypertext Transfer Protocol (HTTP) 404 error, also commonly known as the 404 Page Not Found error, is a response code indicating that the client was able to reach the desired server but could not find the page or file for which it was looking. In simpler terms, the Internet browser was able to connect to the website in question, but the requested page was not found.
Every time a request is made from a client to a server, the HTTP protocol sends what is called HTTP headers with a status code. For a normal website, the status code is “200 OK,” which is the standard response for successful HTTP requests. Other status codes might be displayed if the website is redirected.
Each numeral in an HTTP 404 error means something. The first numeral “4” indicates that a client error has occurred, so the server is saying that there was an error on the client’s end, such as a typo. It also indicates that the error might not be permanent. The middle “0” indicates a general syntax error. The last “4” indicates which particular error was made out of the 400 client error group, which includes “400 Bad Request,” “401 Unauthorized” and “403 Forbidden.”