ELI5: How does Database Replication work?

Database replication is a way to make sure that data in a database is available and can be accessed quickly, even if something happens to the main database. Here's how it works:

1. **Making a Copy**: First, a copy of the main database is made. This copy is called a "replica" or "mirror" of the main database.
2. **Synchronization**: The copy is kept up-to-date with the main database. This is done in real-time, so that any changes made to the main database are also seen in the replica.
3. **Distribution**: The replica can be stored in a different location, which can be on the same computer or a different one. This means that if the main database is not available, the replica can be used instead.
4. **Types of Replication**: There are different ways to set up database replication. For example, in "active/active" replication, both the main and replica databases can be used at the same time. In "transactional replication", the replica gets updates as they happen in real-time.
5. **Benefits**: Database replication helps keep data safe and available. It can also improve performance by reducing the load on the main database, especially during peak usage times.

In summary, database replication works by making a copy of the main database, keeping it up-to-date, and storing it in a different location. This ensures that data is always available, even if something happens to the main database.