Wikipedia
An i-broker is a "banker for data" or "ISP for identity services" — a trusted third party that helps individuals and organizations share private data the same way banks help exchange funds and ISPs help exchange e-mail and files. The term was introduced in the Social Web paper describing how a new layer of Internet infrastructure is possible based on the OASIS XRI and XDI specifications. However the concept of an i-broker is not specific to any one technology or protocol, but rather a business and social function, similar to that of a bank or an ISP.
Just as banks offer a wide range of financial services associated with an account, and ISPs a wide range of Internet services, i-brokers will offer a wide range of identity and data sharing applications. As with e-mail and web hosting, some i-brokers will specialize in services for personal account holders, some will concentrate on the business and government market, and some will be full-service brokers handling all types of accounts. In all cases, the sensitivity of the data involved will demand of i-brokers the same high standards of accountability and trust demanded in the global banking system. Unlike the banking system, however, it is unlikely i-brokers will be highly regulated. Instead good behavior is more likely to be enforced by online reputation systems.
Just as people use different banking and brokerage accounts for different financial services, they are likely to use multiple i-brokers for sharing different sets of data (personal, financial, medical, vocational, etc.). However, with data sharing technology such as XDI link contracts, an account holder can choose to link all of their i-broker accounts, or selected accounts, or none at all — the same way a web site author determines which pages on the site link to each other.
As more digital identity protocols and standards come to market, other types of service providers will be in a position offer i-brokering services, including social networks, portals, domain name registrars, internet service providers (ISPs), banks, insurance companies, wired and wireless phone companies and e-commerce sites.
XDI.org is the first public trust organization for i-brokers. XDI.org maintains a set of Global Services Specifications (GSS) governing i-broker accreditation and policy management, and a set of I-Services Specifications (ISS) defining interoperable identity services.
I-Brokers are sometimes referred to as a homesite, or PIP (Personal Identity Provider), or IdP (Identity Provider)