Welcome to the C# tutorial. C# (pronounced "See-Sharp") is a programming language developed by Microsoft for creating rich web or windows applications. C# runs on the .NetFramework and is a windows only language, so any programs you make in C# generally won't work with Linux or Apple OS. C# is widely used in the business industry and is a powerful object oriented programming language.
The current tutorials are all tested with Visual Studio 2010 / 12 and use the .NetFramework 4. Version 4.5 will be able to support the NetFramework 4.