404 is an HTTP status code. According to the W3C, 404 Not Found is only supposed to be used in cases where the server cannot find the requested location and is unsure of its status. If a page has permanently been deleted, it is supposed to use 410: Gone to indicate a permanent change. But has anyone ever seen 410? If you notice that there are consistent errors, look and see what the referring document is. Do you have a broken link on your site? Does another site link to you with a misspelled URL? These are things you can correct easily, which will help prevent 404 errors on your website.
Some have whimsically described “HTTP 404” as a kind of signal that you have dropped off the edge of the world; in reality, the 404 is actually more like an “access denied.” Check out our 404 page which has also been listed as one of the best on the Net by the 404 Research Lab.
Special thanks to all who have listed our 404 as one of their favorites… we always appreciate a good review! 
