Methods differ widely in how resolution works: did:key encodes a public key directly, did:web fetches /.well-known/did.json over HTTPS (so it inherits DNS and WebPKI trust), did:jwk wraps a JWK, and ledger-based methods anchor documents on blockchains. A DID document's verificationMethod entries hold keys as JWKs or multibase strings, referenced by authentication and assertionMethod.
DIDs identify issuers and holders in some verifiable credential ecosystems. The EU Digital Identity Wallet architecture instead relies mainly on X.509 certificates and trusted lists, so DID support matters for specific ecosystems rather than universally. Choosing a method means choosing its governance, availability and key-rotation behavior.