C# sealed keyword applies restrictions on the class and method. If you create a sealed class, it cannot be derived. If you create a sealed method, it cannot be overridden.
Note: Structs are implicitly sealed therefore they can't be inherited.
C# Sealed class
C# sealed class cannot be derived by any class. Let's see an example of sealed class in C#.
Compile Time Error: 'Dog': cannot derive from sealed type 'Animal'
C# Sealed method
The sealed method in C# cannot be overridden further. It must be used with override keyword in method.
Let's see an example of sealed method in C#.
Compile Time Error: 'BabyDog.run()': cannot override inherited member 'Dog.run()' because it is sealed
Note: Local variables can't be sealed.
Compile Time Error: Invalid expression term 'sealed'