Cloud computing, often referred to as simply "the cloud", is the delivery of on-demand computing resources—everything from applications to data centers—over the Internet on a pay-for-use basis. OpenStack is the most widely used open source cloud platform. The OpenStack cloud was originally created by combining the Nebula cloud computing project from NASA with the Swift Object storage project from Rackspace. This chapter provides OpenStack installation tips, shows how to use OpenStack and how to log into OpenStack instance with secure shell (SSH), and discusses OpenStack Keystone. The OpenStack Dashboard is a GUI that allows control of the various OpenStack components. The Dashboard is implemented as a separate application, called Horizon. Keystone is accessed using the OpenStack Identity API, and must be configured before use. Keystone allows different kinds of authentication; these include: username/password, token-based including: Universally Unique Identifier (UUID) tokens; public key infrastructure (PKI)/ public key infrastructure compressed (PKIZ) tokens; and Fernet tokens, and Amazon Web Services.