I can't say it any better than this video.

Or if you live outside the USA, below is a lecture/rant from the perspective from someone who lives abroad.

As my final Christmas gift to you, you need to watch this video. On Christmas Eve, I was chatting to my sister about video, music, and the Internet. I asked her what she knew about SOPA. She didn't know what SOPA is. Honestly, I didn't expect her to as most people I know haven't a clue that something fundamental is happening to the Internet. I have been struggling often to figure out a way to express the dangers with SOPA and (in Canada) Bill C-11. As Canadian's there isn't a whole lot we can do to fight SOPA but C-11 is Canadian and is similar and we can fight it.

In a nutshell, these bills will destroy the Internet in the name of perceived copyright infringement. Not proof of infringement. If a recording company or label thinks you have something they own, your site can be taken down without notice. At least, this is what the language says at the moment. I beg you all to educate yourself about this stuff. It is important. I talk about this stuff with Andrew Currie, Mike Vardy, and Anthony Marco all the time. Why not check us out and get involved in the discussion?

You all realize that web sites such as Twitter, Google, Facebook, and any other site featuring media you did not create are in jeopardy? You know this, right? If you have a blog and you post a video, it will be taken down. Not the video. Your web site.

See?