B.1. The Platform-Independent Nature of .NET

Historically speaking, when programmers used a Microsoft development language (e.g., VB6) or Microsoft programming framework (e.g., MFC, COM, or ATL), they had to resign themselves to building software that (by-and-large) executed only on the Windows family of operating systems. Many .NET developers, accustomed to previous Microsoft development options, are frequently surprised when they learn that .NET is platform-independent. But it's true. You can create, compile, and execute .NET assemblies on operating systems other than Microsoft Windows.

Using open source .NET implementations such as Mono, your .NET applications can find happy homes on numerous operating systems, including Mac OS X, Solaris, AIX, and numerous flavors of Unix/Linux. Mono also provides an installation package for (surprise, surprise) Microsoft Windows. Thus, it is possible to build and run .NET assemblies on the Windows operating system, without ever installing the Microsoft .NET Framework 4.0 SDK or the Visual Studio 2010 IDE.