This document provides an overview and introduction to the Keystone identity service in OpenStack. It defines key concepts in Keystone including users, tenants, roles, tokens, services, and endpoints. It also provides examples of using the keystone CLI to list and get information about users, tenants, services, and endpoints. The document concludes by assigning homework of setting up additional roles, endpoints, and services in Keystone to enable the Glance image service, and installing Glance in preparation for the next session.