How a database can be recovered from failed transaction?

A database can be recovered from a failed transaction using a method called rollback, which reverts the database to its last consistent state before the transaction began. This is typically achieved through a transaction log that records all changes made during transactions. If a failure occurs, the database management system (DBMS) uses the log to undo any changes made by the incomplete transaction, ensuring data integrity. Additionally, in some systems, checkpointing can be used to minimize the amount of data that needs to be rolled back.