Elasticsearch cross-cluster replication (CCR) is a feature that allows indices to be replicated across multiple Elasticsearch clusters, enhancing high availability and disaster recovery capabilities while facilitating CDN-like data architectures. Initially introduced in Elasticsearch 6.5 as a beta and later as a Generally Available feature in 6.7, CCR operates on a leader/follower model where data from a leader index is replicated to one or more follower indices, which accept no direct writes. Bi-directional replication permits seamless data access and writing across clusters without manual failover, ideal for immutable index-only workloads like logs and metrics. The tutorial provides a step-by-step guide to setting up CCR with local clusters, outlining the necessary configurations via APIs and Kibana UI, such as defining remote clusters, creating indices, and setting up read and write aliases, to ensure both data replication and high availability without requiring application changes. The CCR feature is licensed under the Platinum tier, with a 30-day trial available, and further resources are suggested for deeper exploration of CCR capabilities.