Sealed Class

The sealed keyword is used to prevent a class from being inherited or to prevent a method from being overridden.
When a class is marked as sealed, it means that it cannot be used as a base class for further inheritance.
Similarly, when a method is marked as sealed, it means that it cannot be overridden in derived classes.

Sealed Class:

public sealed class FinalClass
{
    // Class members and methods
}

// This will cause a compile-time error
public class DerivedClass : FinalClass
{
    // Cannot inherit from a sealed class
}

Sealed Method:

public class BaseClass
{
    public virtual void Method1()
    {
        Console.WriteLine("Method1 in BaseClass");
    }

    public sealed void Method2()
    {
        Console.WriteLine("Method2 in BaseClass");
    }
}

public class DerivedClass : BaseClass
{
    // This will cause a compile-time error
    public override void Method1()
    {
        Console.WriteLine("Method1 in DerivedClass");
    }
}