Chances are, you’ve come across the “404 Not Found” error page. 404 refers to the HTTP status code a page receives when a URL does not exist. So every time a user visits a link that doesn’t live on your site, they will be served a default 404 page informing them of that fact. There is a story that the 404 code came from the number of the first room to hold a WWW database server, but this is a myth. It’s just the number assigned by the W3C. If you’d like to see a 404 page in action, you can see an example on Elegant Themes.
Sent from my Samsung Galaxy smartphone.