Okay, so have you ever been to a pool or a park where there are people who keep you safe and make sure you don't get hurt? That's called a lifeguard or a park ranger.
Now imagine that there are lots of people who do that kind of job all over the world! That's called being a professional patroller.
And just like how you have a teacher at school who helps you learn, these professional patrollers have their own group where they can work together and learn from each other. It's called the Association of Professional Patrollers.
It's kind of like a club where they can talk to each other and share their ideas and experiences. They can learn about new safety techniques and equipment, teach each other cool tricks, and help make parks and pools even safer for you and all the other kids to play in. Pretty neat, huh?