The term "Cloud OS" (Cloud Operating System) generally carries two meanings. First, it can refer to cloud management software platforms that orchestrate cloud computing resources, manage provisioning (resource allocation for virtual machines), and provide operational management of cloud infrastructures—examples include OpenStack, Windows Azure, and VMware vCloud. Second, it can indicate client operating systems specifically designed for cloud access, like Google's Chrome OS. However, the term is more commonly associated with the former meaning.
An operating system (OS) traditionally handles the allocation and management of hardware resources within a single computer—including CPU, memory, and input/output interfaces—to ensure smooth overall system operations. From an application viewpoint, the OS abstracts underlying hardware details, enabling software use without requiring intricate hardware knowledge. Extending this concept to the wider context of cloud computing gives rise to the concept of a Cloud OS.
The term Cloud OS began appearing in media around 2013. Earlier, it was generally known by other terms such as "IaaS platform software." A notable example was Microsoft's introduction in January 2013, when they branded a combination of Windows Server and Windows Azure as their "Cloud OS." Similarly, in June 2013, HP announced the "HP Cloud OS," an integration built upon OpenStack and HP technologies.