A 404 server response status code means “page not found” and the 410 server response simply means “gone”.

For as long as I can remember, search engines have treated both these codes in the same way, with them both meaning that nothing is returned on a certain URL.

But reading a Google webmaster help thread from yesterday, Google employee John Mu stated that this is no longer the case and that Google is now treating these codes slightly differently.

The basic message appears to be that if a page has never existed on a specific URL, it uses a 404 server response code, whereas a 410 server response code should be used if the page has existed but never will again moving forward.

I don’t think this is important enough to go rewriting your websites, but it may be worth noting if you are ever in that position.

John Mu’s post in full:

“I followed up on the 404 vs 410 thing with the team here. As mentioned by some others here & elsewhere, we have generally been treating them the same in the past.

However, after looking at how webmasters use them in practice we are now treating the 410 HTTP result code as a bit “more permanent” than a 404. So if you’re absolutely sure that a page no longer exists and will never exist again, using a 410 would likely be a good thing. I don’t think it’s worth rewriting a server to change from 404 to 410, but if you’re looking at that part of your code anyway, you might as well choose the “permanent” result code if you can be absolutely sure that the URL will not be used again. If you can’t be sure of that (for whatever reason), then I would recommend sticking to the 404 HTTP result code.

In the worst case, the 410 will be treated the same as a 404; in the best case it’ll be a bit quicker & stickier .” [Source: Google webmaster central blog, 27/10/09]