Fan Out
In plain terms
Distributing one message or task to many recipients or workers.
Going deeper
Fan-out sends a single event to multiple consumers or splits work across many workers in parallel. It multiplies one input into many outputs.
Under the hood
Used in pub/sub and parallel processing; fan-out-on-write precomputes per-recipient feeds (e.g., timelines).
Examples
Social media feeds, pub/sub, parallel processing, notifications, SNS.
Think of it like...
Like a single announcement copied and delivered to every department at once.