A primer on DIDs before we go into the Core Specification of GeoDIDs
Decentralized identifiers (DIDs) are a new type of identifier that enables verifiable, decentralized digital identities. A DID identifies any subject (e.g., a person, organization, thing, data model, abstract entity, etc.) that the controller of the DID decides that it identifies. DIDs are URIs that associate a DID subject with a DID document allowing trustable interactions associated with that subject.
Each DID document can express cryptographic material, verification methods, or service endpoints, which provide a set of mechanisms enabling a DID controller to prove control of the DID.
Figure 1: The basic architecture of the DID
To learn more about DIDs and why they're useful: