ASP.NET
This is the latest incarnation of Microsoft's middleware for the Internet. ASP.NET is built upon the .NET Framework. The .NET Framework has two main components: the common language runtime (CLR) and the .NET Framework class library. The CLR is the foundation of the .NET Framework. You can think of it as an agent that manages code at execution time for both Windows and ASP.NET applications. The class library, the other main component of the .NET Framework, is an object-oriented collection of reusable components that you can use to develop applications for both Windows and the Web. ASP.NET is therefore the required environment that supports developers who use the .NET Framework to develop Web-based applications. The .NET framework is a free download, but the development tools can be pricey.