[Starting with the .NET Framework 4.5, Windows Identity Foundation (WIF) has been fully integrated into the .NET Framework. The version of WIF addressed by this topic, WIF 3.5, is deprecated and should only be used when developing against the .NET Framework 3.5 SP1 or the .NET Framework 4. For more information about WIF in the .NET Framework 4.5, also known as WIF 4.5, see the Windows Identity Foundation documentation in the .NET Framework 4.5 Development Guide.]
Relying Party (RP)
When you build an application that relies on claims, you are building a relying party (RP) application. Synonyms for an RP include “claims aware application” and “claims-based application”. Web applications and Web services can both be RPs. A relying party (RP) application consumes the tokens issued by a Security Token Service (STS) and extracts the claims from tokens to use them for identity related tasks. The STS supports two types of RP application: ASP.NET Web applications, and Windows Communication Foundation (WCF) Web services. WIF offers functionalities to help you build RP applications. For more information, see How to: Build an ASP.NET Relying Party Application and How to: Build a WCF Relying Party Application.