MySQL replication is a process of copying data from one database server (master) to one or more servers (slaves). MySQL supports several replication topologies with Master/Slave topology being one of the most well-known topologies in which one database server acts as the master, while one or more servers act as slaves. By default, the replication is asynchronous where the master sends events that describe database modifications to its binary log and slaves request the events when they are ready.

Source: LXer – How to Configure MySQL (MariaDB) Master-Slave Replication on Debian 10