What are sealed classes in Java 17?

Today, I updated my Java version from 16 to 17, and I found that sealed classes is a new feature in it. I think it can be declared like this:

public sealed class Main permits AClass, AnotherClass {
}

But, what is the use of sealed classes in Java?

I also knew that it was a preview feature in JDK 15.

You can follow this link for examples.

In short, sealed classes gives you the control of which models, classes etc. that can implement or extend that class/interface.

Example from the link:

public sealed interface Service permits Car, Truck {

    int getMaxServiceIntervalInMonths();

    default int getMaxDistanceBetweenServicesInKilometers() {
        return 100000;
    }
}

This interface only permits Car and Truck to implement it.