MySQL Replication Primer
High Availability & Scalability with Replication in MySQL
Caveat — Notes on replication taken in 2017. This content is updated till MySQL 5.7 GA release.
What is Replication
Replication enables data from one MySQL database server (the master) to be copied to one or more MySQL database servers (the slaves). Replication is asynchronous by default; slaves do not need to be connected permanently to receive updates from the master