The TAP protocol is an internal part of the Couchbase Server system and is used in a number of different areas to exchange data throughout the system. TAP provides a stream of data of the changes that are occurring within the system.

TAP is used during replication, to copy data between vBuckets used for replicas. It is also used during the rebalance procedure to move data between vBuckets and redestribute the information across the system.