Well kiddo, have you ever seen a sailboat? They use something called a sail to catch the wind and move across the water. A gunter rig is a type of sailing rig that uses a special kind of sail called a gunter sail.
So, what's a gunter sail? Imagine a big piece of cloth that has a long, skinny pole running through the middle of it. This pole is called the "gaff" and it holds the sail up high in the air. There's also a shorter pole called the "topmast" that sticks up even higher than the gaff, and it helps the sail catch even more wind.
Now, why would you want to use a gunter rig instead of a regular sail? Well, gunter sails are really good at catching wind at different angles, which can make the boat go faster and handle different wind conditions. They're also easier to hoist and lower than some other types of sails, so you don't need as many people to help you.
Overall, a gunter rig is just one way to use a sail to help a boat move across the water. It's kind of like having a really big kite to help push you along!