Memento
In plain terms
A pattern capturing an object's state for later restoration.
Going deeper
The Memento pattern saves an object's internal state externally so it can be restored later, without exposing its internals. It enables snapshots and undo.
Under the hood
Preserves encapsulation while supporting rollback; storage and memory cost grow with snapshots.
Examples
Undo functionality, save states, editor history, rollback, snapshots.
Think of it like...
Like saving a game checkpoint you can reload to undo later mistakes.