Value types can not store the null values,nullable feature added in c#2.0.now onwords we can able to add null values to value types. ex: int x=null; \\invalid int? x = null; \\ valid

mostly value types cannot be assigned as null.(Eg:int a =null) To break this c# implemented null-able types so that we can assign value types as null.(Eg : int? a) this specifies a might be null

Variable types does not hold null values so to hold the null values we have to use nullable types. So nullable types can have values either null or other values as well.Eg: Int? a= null;