BBC:

The user-generated news site Reddit and the blog Boing Boing have also said they will take part in the "blackout".
The sites' webmasters are opposed to the Stop Online Piracy Act (Sopa) and Protect Intellectual Property Act (Pipa) being debated by Congress.
However, Twitter has declined to take part in the shutdown.
Wikipedia's founder, Jimmy Wales, told the BBC: "Proponents of Sopa have characterised the opposition as being people who want to enable piracy or defend piracy.
"But that's not really the point. The point is the bill is so over broad and so badly written that it's going to impact all kinds of things that, you know, don't have anything to do with stopping piracy."