Authentication schemes are used in UME authentication only. Portal iViews and Web Dynpro applications always use authentication schemes. J2EE Web applications may use them depending on whether they were programmed to use UME or container-based authentication. You only need to read this section if your applications use UME authentication.
For an overview of what an authentication scheme is, see Authentication Scheme.
Authentication schemes are defined in the authschemes.xml file which you can change in the Config Tool. For more information, see Changing the authschemes.xml File.