bigchaindb/docs/source/nodes/node-cluster-federation.md

Terminology: Nodes, Clusters & Federations

A BigchainDB node is a server or set of closely-linked servers running RethinkDB Server, BigchainDB Server, and other BigchainDB-related software. Each node is controlled by one person or organization.

A set of BigchainDB nodes can connect to each other to form a cluster. Each node in the cluster runs the same software. A cluster contains one logical RethinkDB datastore. A cluster may have additional servers to do things such as cluster monitoring.

The people and organizations that run the nodes in a cluster belong to a federation (i.e. another organization). A federation must have some sort of governance structure to make decisions. If a cluster is run by a single company, then the federation is just that company.

Confusingly, sometimes we refer to a cluster as a federation. You can probably tell what we mean from context.