Redo mechanisms are essential components in database management systems that ensure data integrity and consistency. They work by reapplying changes made to the database during transactions, allowing the system to recover from failures. This process is crucial for maintaining accurate records, especially in environments where multiple transactions occur simultaneously. When a transaction is committed, the redo mechanism logs the changes in a redo log. In the event of a system crash or failure, the database can use this log to restore the last known good state by redoing the operations that were successfully completed. This helps prevent data loss and ensures reliability.