Software Engineering · Architecture
Designating one system or table as the definitive record for a piece of data, so every other copy defers to it instead of drifting out of sync.
Example: Storing a user's email in one canonical table instead of three that can disagree.
In practice: Distributed systems complicate this ideal, since services often keep local copies for performance — the trick is making one source authoritative and treating the rest as derived caches.