SOPA:"Shut down first, then don't ask questions"

I am not going to say anything better than what the major sites like Google or Wikipedia are going to say, so here are the links to their pages explaining it.

Remember that in the USA, we are supposed to be the land of the Free, respecting an individual's rights, which are not to be taken away without Due Process. The protest is not about allowing piracy; it is about ensuring that everyone is given Due Process in determining wrongdoing.

More info at http://sevensages.com/Company-News/SOPA-Protest-Blackout.html

Also, many other sites explain it even better.

http://americancensorship.org/infographic.html