Merge replication is a type of database replication where changes made at multiple sites can be synchronized and merged, allowing data to be updated at various locations independently and then later reconciled. This approach is commonly used in distributed systems where multiple databases need to operate autonomously but must eventually sync with a central repository or among each other. The system tracks changes through conflict resolution mechanisms, ensuring that updates from different sources do not cause data inconsistencies. Merge replication is typically used in scenarios where data is continuously updated in different locations, such as mobile applications or remote office setups.