Why is the read-committed isolation level used in database management systems?

The read-committed isolation level in a DBMS guarantees that a transaction only sees data that has been committed by other transactions. This prevents reading "dirty" data — data that has been modified but not yet committed.

Applying this level of isolation helps avoid errors related to reading intermediate data states, but it allows non-repeatable reads and phantom reads.

Example: if one transaction updates a record, another transaction operating at the read-committed level will not see these changes until the first transaction commits. This balances data integrity and performance.