What does "Durability" mean in ACID?

Durability means that once a transaction completes successfully, its results are saved permanently, even if a system crash, power outage, or server restart happens right afterward.

The system commits changes to persistent storage (e.g. a transaction log or disk) so they can be recovered.

Example: if a crash happens right after a money transfer, the data still shows the transfer as already completed after the restart - the transaction is never lost.