CloudStack is apache foundation managed open-source cloud computing software for creating, managing, and deploying infrastructure cloud services. It uses existing hypervisors such as KVM, VMware vSphere, VMware ESXi, VMware vCenter, and XenServer/XCP for virtualization. In addition to its own API, CloudStack also supports the Amazon Web Services (AWS) API[2] and the Open Cloud Computing Interface from the Open Grid Forum.
Rather than explain CloudStack here. (I am still learning cloudstack). I think your time would be better served if you read it from the Cloud Stack Source. Here’s the link: The Current version is 4.6
http://docs.cloudstack.apache.org/projects/cloudstack-installation/en/4.6/
