sealed -- C# Keyword

sealed  -- C# Keyword

•  When applied to a class, the sealed modifier prevents other classes from inheriting from it.
•   In the following example, class B inherits from class A, but no class can inherit from class B.

class A {}  
sealed class B : A {}

readonly -- C# Keyword

readonly -- C# Keyword

•  The readonly keyword is a modifier that you can use on fields.
•   When a field declaration includes a readonly modifier, assignments to the fields introduced by the declaration can only occur as part of the declaration or in a constructor in the same class.

readonly <data Type> <var Name>;