Okay kiddo, so you know how some people like to ride bikes or tricycles? Well, there are some grown-up folks who really like to ride these kinds of vehicles too, but they make them very special and fancy!
The International Human Powered Vehicle Association (or IHVPA for short) is a group of these special bike and trike riders from all over the world who come together to have races and competitions. They call these special bikes "human powered vehicles" because they rely only on people like you and me to move them, instead of using motors or engines.
The IHVPA has rules for these races to make sure they are fair and safe, and they even have different categories depending on things like the shape of the vehicle or how many people are riding it. Sometimes they even have races that go for really long distances, like across an entire country!
Being part of this group is a lot of fun, because you get to meet other people who love human powered vehicles and compete with them to see who is the best. It's a little bit like going to a big playground with all your friends, but instead of just playing on swings and slides, you get to ride really cool bikes and trikes!