Censorship can also occur on the listening end. One very prominent form is internet filters. Not only are these unjust, they can be downright ridiculous. Some schools block political advocacy groups. One school blocked this page because "manga" was in the title. Never mind the fact that it doesn't even mention manga, because "manga" is Spanish for "sleeve". Never mind that anime porn is called hentai. Another school blocks Pro-life America's site as "Tasteless and Offensive". They can also often be surpassed by something as simple as the Google Cache. Google Translator is blocked at one school. Some parents censor their children's Internet access, either to "protect" them or to maintain mindless obediance (for example, blocking hothotbabesXXX.com and youthrights.com respectively).
We clearly are not doing well preparing our children for the real world. If we were, we would be able to trust them online. We would trust that they would not give out personal information, or download a virus, or be traumatized by porn when we never tell them what sex is. A computer is not going to kidnap your child and sodomize her in a dark alley. In fact, children are far more likely to be abused by those close to them than the shady man hiding in the bushes or some pervert they meet online. In fact, that pervert they meet online can't do anything to them over the computer. What scares me is that some people want to get rid of online anonymity. This may mean less jerks online, but it will also mean a more dangerous world. And jerks online can't do much. That is, as long as you remain anonymous.
This all goes back to the underlying notion that young people are bad people. All teens are doing drugs. Teen sex is bad. And so on.
Teach your teen. Trust your teen. Treat your teen as an equal.