This package encapsulates the APIs to interact with Peers and Orderers of the Fabric network to deploy chaincodes, send transaction invocations and perform chaincode queries. There is a separate package that interacts with the Fabric member service to manage user certificates lifecycle such as register, enroll, renew and revoke, and that is called fabric-ca-client.
For application developer documentations, please visit http://fabric-sdk-node.readthedocs.io/en/master/