Rotten tomatoes is a website where people go to see if a movie or TV show is good or bad. Just like when you eat a tomato and it's bad and tastes yucky, movies and TV shows can be bad too. The website has a scale that says if a movie or show is good, bad, or just okay. It uses a special system called the "Tomatometer" to decide if a movie or show is good or bad.
Think of it like a big group of kids all watching the same movie. If most of the kids think the movie is good, then the movie gets a good rating on Rotten Tomatoes. But if most of the kids think the movie is bad, then the movie gets a bad rating on Rotten Tomatoes.
So when you want to know if a movie or TV show is good or bad, you can look on Rotten Tomatoes to see what lots of other people think about it. That way, you can decide if you want to watch it or not!