Core ID: Your identity, used for high-trust actions — the things where it genuinely matters that you are you.
Aliases: An unlimited number of anonymous identifiers for everyday activity. You can use a different one wherever you like.
Why the split exists: Because everyday activity runs through aliases rather than one single identifier, different services cannot cross-reference your behaviour across the internet.
A simple rule of thumb: Use an alias by default. Reach for the Core ID only where a service genuinely needs a verified, high-trust identity.
Both belong to you: Core ID and aliases are part of the same self-owned identity held on your device, not accounts issued to you by the services you use.