Cross-Cluster Replication (CCR) in Elasticsearch 6.7 is a feature that enables data replication across multiple datacenters or Elasticsearch clusters without the need for additional technologies. By configuring replication at the index level, CCR supports various strategies, such as data locality and centralized reporting, making it suitable for diverse use cases like maintaining data close to application servers or replicating banking data globally for reporting purposes. The CCR feature is managed through Elasticsearch's APIs and Kibana UI, offering options like auto-follow patterns for time-based indices and defining remote clusters for replication. Security requirements necessitate specific privileges for users in both source and target clusters. CCR is a platinum-level feature that can be trialed for 30 days, and it provides flexibility in architecture, including production and disaster recovery setups, multi-datacenter deployments, and bi-directional replication. The tutorial outlines setting up CCR, creating indices for replication, and testing the setup, while administrative APIs facilitate management tasks like pausing, resuming, or converting a follower index to a normal index.