How Merge Replication Works
Merge replication is implemented by the SQL Server Snapshot Agent and Merge Agent. If the publication is unfiltered or uses static filters, the Snapshot Agent creates a single snapshot. If the publication uses parameterized filters, the Snapshot Agent creates a snapshot for each partition of data. The Merge Agent applies the initial snapshots to the Subscribers. It also merges incremental data changes that occurred at the Publisher or Subscribers after the initial snapshot was created, and detects and resolves any conflicts according to rules you configure.
The following diagram shows the components used in merge replication.
For detailed information about how merge replication works, see the following topics: