OpenStack is a collection of open source software projects that enterprises/service providers can use to setup and run their cloud compute and storage infrastructure. Rackspace and NASA are the key initial contributors to the stack. Rackspace contributed their "Cloud Files" platform (code) to power the Object Storage part of the OpenStack, while NASA contributed their "Nebula" platform (code) to power the Compute part. OpenStack consortium has managed to have more than 150 members including Canonical, Dell, Citrix etc.
There are 5 main service families under OpenStack
Nova - Compute Service
Swift - Storage Service
Glance - Imaging Service
Keystone - Identity Service
Horizon - UI Service
The below diagram shows a simple representation of interaction between keystone and dashboard with the remaining OpenStack components.
