Online services that offer high-level APIs to abstract away many low-level aspects of the underlying network infrastructure, such as physical Cloud Computing, location, data partitioning, scaling, security, backup, etc. are known as "Infrastructure as a Service" (IaaS). The virtual machines are operated as guests by a hypervisor. Large numbers of virtual machines can be supported by pools of hypervisors within the cloud operating system, and services can be scaled up and down in response to changing client needs. A single Linux kernel that is directly installed on the physical hardware powers each segregated partition where Linux containers operate. The fundamental Linux kernel technologies used to manage, secure, and isolate containers are cgroups and namespaces. Since there is no hypervisor overhead, containerization is more performant than virtualization.
