Okay, so let's say you have a toy that you really like to play with, but your grown-up says that it's not a good toy and you can't play with it anymore. That's kind of what the anti-pornography movement in the United States is all about.
Some grown-ups don't like when other grown-ups watch or look at things that they think are inappropriate or harmful, like pictures or videos of people doing sexual things. They worry that it can hurt people's feelings or make them do bad things. So, they started a movement to try to stop people from making or sharing these pictures and videos.
They believe that these things are not just bad, but they are also dangerous and can hurt people's minds and bodies. They think that it is important to protect people, especially children, from seeing this kind of stuff.
That's why there are laws that restrict pornography in some parts of the United States. Some people think these laws are a good thing because they believe that it's important to keep children safe and teach them about healthy relationships. Other people think these laws go too far and are a violation of freedom of speech.
So in short, the anti-pornography movement in the United States is a group of grown-ups who want to stop people from looking at or making pictures and videos of sexual things because they think it's not good for people's minds and bodies.