An exclusive lock is a type of lock used in database management systems to control access to a resource, such as a row or table. When an exclusive lock is applied, it prevents other transactions from reading or writing to the locked resource until the lock is released. This ensures that the data remains consistent and prevents conflicts during updates. Exclusive locks are essential for maintaining data integrity in multi-user environments. They are typically used during operations that modify data, such as INSERT, UPDATE, or DELETE commands. By using exclusive locks, systems can avoid issues like lost updates or dirty reads, ensuring reliable data handling.