One of the curious constructions of the Internet is the term identity provider. You don’t need anyone to provide you with an identity, of course. You have an innate one by virtue of being human. Rather, so-called identity providers, or IDPs, provide you with an identifier, a means of recording attributes important to that provider, and some method of proving it’s you – usually a password.
This is not surprising since online identity has traditionally been viewed through the lens of an organization and its needs, not the individual and his or her needs. Identity systems are created to administer identifiers and attributes within a specific domain. The result: people end up with hundreds of online personas at hundreds of organizations. Each of these administrative identity systems is proprietary and owned by the organization that provides it; you really don’t have an online identity that’s independent of these many systems. Got a new address, or an updated credit card number? You’ll have to deal with each of these systems one at a time in whatever manner they require.