Replication enables automatic, asynchronous copying of objects across Amazon S3 buckets. Buckets that are configured for object replication can be owned by the same AWS account or by different accounts.

What does S3 replicate?

By default Amazon S3 replicates the following: Objects created after you add a replication configuration. Unencrypted objects. Objects encrypted at rest under Amazon S3 managed keys (SSE-S3) or KMS key stored in AWS Key Management Service (SSE-KMS).

What is region replication?

Cross Region Replication is a feature that replicates the data from one bucket to another bucket which could be in a different region. It provides asynchronous copying of objects across buckets. Suppose X is a source bucket and Y is a destination bucket.