The Raft Consensus Protocol is the set of quorum guidelines that CockroachDB follows to ensure each range is consistent. It’s an algorithm that makes sure all copies agree on changes to data. A “leader” is elected for each range (leaders are also known as Leaseholders), to coordinate changes for that range, and the two other ranges are called “followers.” Changes get entered in the leader’s log, then the leader sends out the changes to the followers, and the changes get entered into their logs. Once this happens, the change is committed to the leader’s data, and then committed to the followers' data.