Rollback
In plain terms
Reverting a system to a previous working version.
Going deeper
A rollback undoes a problematic deployment by restoring the prior version, quickly recovering from failures. It's a key safety mechanism.
Under the hood
Fast rollback needs versioned artifacts and careful handling of database migrations.
Examples
Reverting a bad deploy, blue-green switch-back, version pinning, hotfix recovery.
Think of it like...
Like hitting undo to return to the last save when a change goes wrong.