In the latest version of the Nostr protocol, the developers have added support for external identities. Users can now specify a URL or other identifier for their external identity, which allows clients to retrieve and display the user's external identity information alongside their profile data. This feature is implemented through the introduction of the `i` tag in metadata events, which can be used to specify external identifiers for the user.

Link: https://github.com/nostr-protocol/nips/blob/master/39.md