[jsmith45]

AT protocol currently supports two different schemes for base identifiers based on w3c's DID system. The DID:PLC scheme is centralized, but not inherently tied to any one host. It is currently hosted and run by the Bluesky PBC, but they want to spin it off to help protect against themselves turning evil. This system lets users change their handle and move to a new personal data server seamlessly.

There is also DID:Web. This one has the downside that you need to continue to control the domain name in question indefinitely, and it can be argued that the domain name system is still a form of centralization. Like PLC users can theoretically change handles to another domain name with this scheme (but must contrinue to control the original domain name). Users can freely move to another personal data server.

AT Protocol can add new DID schemes in the future to avoid these downsides, with the caveat that users cannot change from DID type to a different one seamlessly, and adding new DID types may potentially require updates by multiple other parts of the ecosystem.