It's 404 week at Webmaster Central

Monday, August 11, 2008

This week we're publishing several blog posts dedicated to helping you with one response code: 404. Response codes are a numeric status (like 200 for "OK", 301 for "Moved Permanently") that a webserver returns in response to a request for a URL. The 404 response code should be returned for a file "Not Found".

When a user sends a request for your webpage, your webserver looks for the corresponding file for the URL. If a file exists, your webserver likely responds with a 200 response code along with a message (often the content of the page, such as the HTML).

200 response code flow chart

So what's a 404? Let's say that in the link to "Visit Google Apps" above, the link is broken because of a typing error when coding the page. Now when a user clicks "Visit Google Apps", the particular webpage/file isn't located by the webserver. The webserver should return a 404 response code, meaning "Not Found".

404 response code flow chart

Now that we're all on board with the basics of 404 errors, stay tuned for even more information on making 404 errors good for users and for search engines.