Serializability
In plain terms
A guarantee that concurrent transactions appear to run one at a time.
Going deeper
Serializability ensures the outcome of concurrent transactions equals some sequential execution of them, the strongest transaction isolation. It hides concurrency anomalies.
Under the hood
The gold standard for isolation; achieved via locking or MVCC, at a performance cost.
Examples
Database isolation, ACID, concurrency control, transactions, MVCC.
Think of it like...
Like many people editing a document but the result looks as if each took a turn.