A serializable transaction operates in an environment that makes it appear as if no other users were modifying data in the application (database).
Two simultaneous transactions occurring within the database at the same time are isolated from one another. They cannot interfere with one another. Intermediate results within a transaction remain invisible to other transactions.
Full serializable access is guaranteed.
While this degree of isolation between transactions is generally desirable, running many applications in serializable mode can seriously compromise application throughput. Serialization devices inhibit Concurrency.