The .NET platform consists of a number of technologies that allow software developers to build Internet-based distributed systems. Individual pieces of these systems, called software components, can be built using several different programming languages and by several different organizations. Through a common set of core functionality, .NET allows these components to work reliably with each other.

Microsoft's core implementation of .NET includes:

• C# (a new programming language)
• the Common Language Runtime (for support of other programming languages)
• a collection of components that provide support for networking, security, and other "base" services commonly needed in distributed applications
• Windows Forms (WinForms) and Web Forms, rich Windows user interface components
• ASP.NET, a new version of Active Server Pages
• ADO.NET, new data access objects in the tradition of the original Active Data Object