# Authentication Authentication is the process of establishing that a claimant controls an identity or account. Passwords, PINs, one-time codes, device approvals, security keys, and biometric checks can all serve as authenticators, but each has different security and recovery properties. ## Notebook evidence [[Scanned_20260730-2016]] maps authentication across Gmail, Google Fi, Apple/iCloud, Facebook, WhatsApp, ID.me, Snapchat, carriers, banks, brokerages, and wallets. PDF page 41 is the clearest multi-platform authentication map; pages 22, 30–31, and 35–42 show how telephone numbers and devices become shared dependencies. ## Relationship to adjacent concepts Authentication is distinct from [[Identity Proofing]], which establishes who a subject is; [[Authorization]], which determines permitted actions; and [[Account Recovery]], which restores access after normal authentication fails. ## Source - [[Scanned_20260730-2016]], PDF pages 22 and 30–42.