1. Keystone is an open source identity and access management platform. It is a service that provides authentication and authorization for users, applications, and services within a cloud environment.
2. Keystone is composed of several components, including the identity services registered within it, an authentication plugin, user and role management, token generation and management, and so on.
3. Keystone acts as the single source for identity in a cloud infrastructure and provides identity services such as user registration, authentication, authorization and credential management.
4. Keystone works in conjunction with other OpenStack services such as Nova, Neutron and Swift to provide federated identity and access control to the applications running on the cloud.
5. Keystone supports both OpenID Connect and SAML based authentication to enable a user to access multiple services running on different clouds with the same set of credentials.
6. Keystone implements Role Based Access Control (RBAC) which enables users to provide restricted access rights in an organization as required.
7. Keystone supports various authentication mechanisms such as password, token, LDAP, OAuth and Multi-factor authentication.