"Lost updates" occur in database systems when two or more transactions read the same data and then update it without awareness of each other's changes. This can lead to one transaction overwriting the changes made by another, resulting in data inconsistency. For example, if Transaction A reads a value, then Transaction B also reads the same value and updates it, Transaction A may later overwrite Transaction B's update when it commits its changes. To prevent lost updates, systems often use techniques like locking or optimistic concurrency control. These methods ensure that transactions are aware of each other's changes, allowing for more accurate and reliable data management. By implementing these strategies, databases can maintain data integrity and avoid the pitfalls of lost updates.