Windows Communication Foundation (WCF) is Microsoft's programming model for using managed code to build unified Web services and other distributed systems that can talk to each other. WCF focuses on connecting XML to programs that are built using development languages supported by Microsoft, such as VB.NET and C#. To support this cross-language communication, WCF uses the extensible Simple Object Access Protocol (SOAP).
WCF is one of the four main products in Microsoft's .NET Framework 3.0, previously known as WinFX. The other three are the Windows Presentation Foundation, or WPF, the Windows Workflow Foundation, abbreviated as either WF or WinWF, and the Windows CardSpace. The .NET 3.0 suite is due to be released around the same time as Windows Vista, Microsoft's upcoming update to its Windows operating system. .NET 3.0 can also be used with Windows XP and Windows 2003 Server.
Many developers still refer to Windows Communication Foundation by its code name, Indigo.