The way the Grapevine works, trust is contextual, and contexts are categorized, with trust inherited from general to specific categories. Example: User A trusts User B in all contexts; B trusts C on medical topics; C trusts D on pulmonary topics; D trusts E on treatment protocols for pulmonary tuberculosis. Each of these links is an attestation stored in nostr, and this is how User A finds User E and benefits from E’s expertise.