Dictionary term
Authentication vs Authorization
Also called auth · authn · authz
Web/DevBeginner
Authentication verifies who a user or system is; authorization decides what that verified identity is allowed to do or access.
In plain English
Authentication checks who you are; authorization checks what you're allowed to do.
Analogy
Showing ID at the hotel desk is authentication; your key card opening only your room is authorization.
Why it matters
Most data leaks in apps are authorization gaps: a user is logged in correctly but can still read another customer's records.
In practice
Supabase Auth signs a client in (authentication), and a Row Level Security policy lets them read only rows where client_id matches their own (authorization).
Related terms
Sources
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