The Web Browser SSO Profile was completely refactored for SAML 2.0. Conceptually, SAML 1.1 Browser/Artifact and Browser/POST are special cases of SAML 2.0 Web Browser SSO. The latter is considerably more flexible than its SAML 1.1 counterpart due to the new "plug-and-play" binding design of SAML 2.0. Unlike previous versions, SAML 2.0 browser flows begin with a request at the service provider. This provides greater flexibility, but SP-initiated flows naturally give rise to the so-called "Identity Provider Discovery" problem, the focus of much research today. In addition to Web Browser SSO, SAML 2.0 introduces numerous new profiles: