To learn how transactions work, you need to acquire a small vocabulary:
Commit. Committing a transaction makes all data modifications performed since the start of the transaction a permanent part of the database. After a transaction is committed, all changes made by the transaction become visible to other users and are guaranteed to be permanent if a crash or other failure occurs.
Roll back. Rolling back a transaction retracts any of the changes resulting from the SQL statements in the transaction. After a transaction is rolled back, the affected data is left unchanged, as though the SQL statements in the transaction were never executed.
Transaction log. The transaction log file, or just log, is a serial record of all modifications ...