The numbers 4-0-4 actually mean something as individual digits in the HTML code. The first 4 is telling you, that there is a mistake on your end, such as a possibly mistyped URL or a request for a page that no longer exists. The 0 just represents a syntax error, basically just means “something isn’t right”. Now after those, the last number could be any one of several digits that indicates the type of error. The 4 in that section means that the page cannot be located.
The 404 Not Found Page comes up on your screen for several different reasons:
1) The page may have been moved.
2) The hyperlink you followed might have a minor error in the URL.
3) There might be a typo on the URL your are requesting.
3) The page may simply be gone.
There is no longer the need to see it as not found page but more like “200 maybe” what does this means? Of course, sometimes you cannot help but remove a page or change the URL, and you will not be able to always prevent the occurrence of an Error Page. But if you can’t avoid it, at least make it work for you with some CSS creativity. You can create and code your custom 404 error page with all the information needed in order of your viewers could still reach you.
If you find there is a page that is consistently getting mistyped, or if you have moved a page that you know many people will be trying to view, instead of just showing them an error page you can automatically redirect them to the correct page. You can use a 404 pageby having it informs your visitor of what happen and links for the new page to inform visitors that the webpage is not available automatically, while at it, why not doing in a creative way?