When Microsoft started their public cloud, they decided that there must be a private cloud stack too, especially, to prepare their infrastructure to run in Azure sometime in the future.

The first private cloud solution was the System Center suite, with System Center Orchestrator and Service Provider Foundation (SPF) and Service Manager as the self-service portal solution. Later on, Microsoft launched the Windows Azure Pack for Windows Server. Today, Windows Azure Pack is available as a product focused on the private cloud and provides a self-service portal (the well-known old Azure portal, code name red dog frontend), and it uses the System Center suite as its underlying technology: