Have you ever clicked on a link only to have it unveil an unfriendly "file not found" message? We know it's a bummer, so now Webmaster Tools offers site owners a way to help all of us click seamlessly through the web.
For years webmasters have been able to view the URLs on their site that are linked from various websites but actually don't exist. Today webmasters can fix these broken links throughWebmaster Tools Crawl error sources. Crawl error sources displays the source URL containing the broken link to their site -- no matter where it exists on the web.
What about any "file not found" URLs that haven't yet been fixed? Let's improve that, too: Webmaster Tools provides site owners with the "file not found" widget, (aka the 404 widget). It's a small snippet of code that can change the message from this unfriendly one: