1**This is the documentation for etcd2 releases. Read [etcd3 doc][v3-docs] for etcd3 releases.** 2 3[v3-docs]: ../docs.md#documentation 4 5 6# Glossary 7 8This document defines the various terms used in etcd documentation, command line and source code. 9 10## Node 11 12Node is an instance of raft state machine. 13 14It has a unique identification, and records other nodes' progress internally when it is the leader. 15 16## Member 17 18Member is an instance of etcd. It hosts a node, and provides service to clients. 19 20## Cluster 21 22Cluster consists of several members. 23 24The node in each member follows raft consensus protocol to replicate logs. Cluster receives proposals from members, commits them and apply to local store. 25 26## Peer 27 28Peer is another member of the same cluster. 29 30## Proposal 31 32A proposal is a request (for example a write request, a configuration change request) that needs to go through raft protocol. 33 34## Client 35 36Client is a caller of the cluster's HTTP API. 37 38## Machine (deprecated) 39 40The alternative of Member in etcd before 2.0 41