Class library or Console applications. I am expert user of Object Oriented Programming having strong skills on Object Oriented Analysis and Design with grip on design patterns and applied polymorphism. .NET Libraries, Tools, Built In classes, Events, Delegates, Multi threading, Linq and Lamda Expression etc can use everything from within .NET framework .NET Framework (1.0, 2.0, 3.0, 4.0, 4.5, 4.5.2)