As we see, even from the very beginning, the Hejlsberg's team started with a complete, flexible, and modern platform, capable of being extended in many ways as technology evolves. This intention became clear since version 2.0.
The first actual fundamental change that took place in the language was the incorporation of Generics. Don Syme, who would later on lead the team that created the F# language, was very active and led this team as well, so it was ready for version 2.0 of the .NET Framework (not just in C# but in C++ and VB.NET as well).
The purpose of generics was mainly to facilitate the creation of more reusable code (one of the principles of OOP, by the way). The name refers to a set of language features that allow classes, structures, interfaces, methods, and delegates to be declared and defined with unspecified or generic type parameters instead of specific types (see https://msdn.microsoft.com/en-us/library/ms379564(v=vs.80).aspx, for...