Have you ever heard of a special group of people who take care of really old and beautiful buildings or places like mountains, rivers, lake, etc? They're called the National Trust. The National Trust people love these places and they want to make sure they stay healthy and safe for a long time.
So imagine you see a really old and beautiful castle in your town, well the National Trust people will come in and make sure the walls of the castle are still strong enough to hold it up, and that the roof doesn't leak when it rains. They also want to make sure that people can still visit the castle and learn about its history so they might put on a little play to show what life was like back then.
Or maybe there's a really pretty mountain you like to hike up, the National Trust people might make sure there are paths to walk up so people don't get lost, and that the mountain stays clean so animals don't eat things that they shouldn't.
So, the National Trust is like a big group of grown-ups who take care of beautiful and important places to make sure they don't get hurt and everyone can enjoy them.