We will call entities with identities "actors", because non-human entities such as companies, organizations, and bots may have identities on a social network.
OAuth is currently the most successful identity standard. OAuth was created to securely transfer user credentials from one site to another. OAuth identity providers became centralized because users could not run or choose their own identity providers.
- Diaspora: User identities in Diaspora are tied to their pod, and cannot be migrated. Diaspora uses the Webfinger protocol to discover users from other pods. User information is returned via hCard, an open microformat standard for identity.
[DIDs](https://w3c-ccg.github.io/did-primer/) are a new type of globally unique identifier that do not require a centralized registration authority, and can serve as a decentralized public key infrastructure. DIDs are a [W3C standard](https://www.w3.org/TR/did-core/).
The format of a DID is: a scheme identifier, followed by the DID method, followed by a method-specific identifier. A simple example: `did:example:123456789abcdefghi`
