SQL Server utilizes replication agents to do different tasks during the replication process. These agents are constantly waking up at some frequency and fulfilling specific jobs. As you can see in Figure 40.20, several replication agent categories are listed under the Job Activity Monitor when you expand the SQL Server Agents branch (SQL Server Agent, Jobs, Job Activity Monitor branch).
Here are the main replication agent categories:
Log Reader Agent
Merge Agent (for updating subscribers)