TL;DR
RLS moves authorization from your app layer into your schema. Security becomes a property of the database, not a discipline every engineer has to remember on every new endpoint.
Four patterns cover ~95% of SaaS: owner-only, team-scoped, public-read/owner-write, and role-based on JWT claims.
A table with RLS enabled and zero policies is a black hole. Nobody reads or writes anything. This is the #1 "why is my query returning empty" cause.
Test with SET LOCAL ROLE authenticated, not in the dashboard SQL editor. The editor runs as superuser and will happily lie to you.
