A 404 error is an HTTP status code that
means the page you were trying to reach on
a website couldn't be found on their server.
To be clear, the error indicates that while the
server itself is reachable, the specific page
showing the error is not.
404 Not Found individual websites frequently
customize error messages. So, keep in mind
that the error might show up in just about any
way imaginable, depending on what website
it's shown from.