Materialization is the process of initially populating the replicate database with a copy of the data from the primary database. Replication Agent requires that you set up and populate each replicate database so that it is in a state consistent with that of the primary database.
Replication Server then replicates incremental changes to the primary data from the primary database to the replicate database.
Chapter 2, “Replication Server Setup,” for information about materializing replicate databases
Replication Server Administration Guide