What is the .NET Framework? The official explanation: .NET Framework is one kind of virtual machines running a systematic programming platform, in a common language runtime (Common Language Runtime) basis, support for multiple languages ??(C #, VB, C / u002B / u002B, Python, etc.) development. NET also for application program interface (API) provides new features and development tools. These innovations can make programmers Windows applications and Web applications as well as components and services (web services) development at the same time. .NET Provides a new reflective object-oriented programming and the programming interface. .NET Designed to be universal enough so that many different high-level languages ??have been put together. The .NET Framework base class library available in all languages ??/ u0028BCL / u0029. In short: .NET Framework is a software development platform, based on this platform for the development of software must run on this platform. Satisfied customer membership management system is based on the .NET Framework platform, so run this satisfied customer to install the software on the client computer must install the .NET Framework. Currently Windows2003, Vista, Win7 operating systems have native .NET Framework, but WindowsXP operating system is not installed by default the .NET Framework, you can automatically or manually install updates through Windows framework.