A 404 Error message means that the page you are trying to reach on a website couldn’t be found on their server.
To clear this up a little more, it means that the server itself is reachable, the specific page showing the error is not.
There are many ways in which a 404 error can come across, essentially though, they are all stating the same thing, the page cannot be reached.
What causes a 404 Error? Technically it is a client-side error, implying that the error is your mistake. Possible reasons include the URL being typed incorrectly, the page has been moved on the website and not redirected correctly or the page may have even be removed from the website.