Why It is not allowed to inherit sealed class

About the first question, i want to add that the sealed class cannot be used as a base class. For this reason, it cannot also be an abstract class. Sealed classes prevent derivation. Because they can never be used as a base class, some run-time optimizations can make calling sealed class members slightly faster.

I want add to the question of Mr.Jagjit Patil ...
Is sealed class is same as final in java??
please anyone give solution to my question.
Thanx in advance..

Compilers are designed to understand keywords. For example, if you type keyword class or int or double in C#, C# compiler knows what it means. Similarly, if a class is sealed, compiler knows if there is any inheritance syntax from a base sealed class, it needs to throw an error.

This is probably a part of parser and lexical analyzer parts of C# Compiler.

That's what I think.

Thanks Shrikanth!
But I wanted to know what happens under the hood when we declare any class as sealed, which prevents us inheriting it.
Do you have any idea?