federation standards can reduce cost by eliminating the need to scale one-off or proprietary solutions. It can increase security and lower risk by enabling an organization to identify and authenticate a user once, and then use that identity information across multiple systems, including external partner websites. It can improve privacy compliance by allowing the user to control what information is shared, or by limiting the amount of information shared. And lastly, it can drastically improve the end-user experience by eliminating the need for new account registration through automatic "federated provisioning" or the need to redundantly login through cross-domain single sign-on. The notion of identity federation is extremely broad, and also evolving. It could involve user-to-user and user-to-application as well as application-to-application use-case scenarios at both the browser tier as well as the web services or service-oriented architecture (SOA) tier. It can involve high-trust, high-security scenarios as well as low-trust, low-security scenarios. The levels of identity assurance that may be required for a given scenario are also being standardized through a common and open Identity Assurance Framework. It can involve user-centric use-cases, as well as enterprise-centric use-cases. The term "identity federation" is by design a generic term, and is not bound to any one specific protocol, technology, implementation or company. Identity federations may be bi-lateral relationships or multilateral relationships. In the latter case the multilateral federation frequently occurs in a vertical market, such as in law enforcement (such as the National Identity Exchange Federation - NIEF) and research and education (such as InCommon). If the identity federation is bilateral, the two parties can exchange the necessary metadata (assertion signing keys, etc.) to implement the relationship. In a multilateral federation, the metadata exchange among participants is a more complex issue. It can be handled in a hub-and-spoke exchange or by the distribution of a metadata aggregate by a federated operator. One thing that is consistent, however, is the fact that "federation" describes methods of identity portability which are achieved in an open, often standards-based manner – meaning anyone adhering to the open specification or standard can achieve the full spectrum of use-cases and interoperability. Identity federation can be accomplished any number of ways, some of which involve the use of formal Internet standards, such as the OASIS Security Assertion Markup Language (SAML) specification, and some of which may involve open-source technologies and/or other openly published specifications (e.g. Information Cards, OpenID, the Higgins