when should you think about database replication?

Hey everyone, I've been thinking a lot about database performance and availability lately. We've all talked about load balancers and sharding, but what about replication? When does it make sense to set up read replicas or even multi-master setups? Is it mainly for handling more reads, disaster recovery, or are there other big advantages I should be thinking about? I'm really curious to hear your experiences and when you've found replication to be super helpful versus just adding more complexity.