Master-Slave replication (MSR) is a model of communication where one device or process has unidirectional control over one or more other devices, often built-in.
In database replication, the master database is regarded as the authoritative source, and the slave databases are synchronized to it.
Usualy MSR database will using doing CRUD for master and READ for slave, so the application not make master database to much load cpu to doing all job.
For how it works lets follow me step by step replicate.I assume you have two mysql server for we do master and slave.