Master Slave database syncronization
How replication happens:


DMLs on Master are written to Binary logs.
Slave connects to master from it's IO thread and reads the binary logs. Save them as Relay log.
Slave's SQL Thread execute the Relay log SQLs to apply the changes.


Now, if you need slave's changes to be reflected on master, you need your master to be replicating from your slave as well. That's known as master-master replication. You can find plenty of posts around that.

By default, all the databases are replicated. If you want to replicate only few of the objects (DB / tables) there are replication filters for that.