With a few exceptions, web status codes are meant to indicate errors. A 404 page shows up when you tried to reach content that wasn't found, for example. However, there's now a code for those times when that absence is all too intentional. The newly published 451 code (a nod to Fahrenheit 451, naturally) lets site hosts and network providers warn you when censorship and similar "legal obstacles" prevent you from seeing web material. In theory, this gives you a much better explanation than the generic 403 "forbidden" code -- and a not-so-subtle hint that you need to jump through hoops to get the truth.