Infrastructure as a Service (IaaS) is the most basic cloud service model, vendors and providers offer computers, as virtual machines, and other resources.

The VM (virtual machines) are run as guests such as KVM or ZEN.  Management of pools of resources by the cloud computing operational support system leads to the ability to scale to support an endless number of virtual machines.

Other resources in IaaS cloud computing include images in a virtual machine image library and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks (VLANs), and software bundles.

For wide area connectivity, the Internet or dedicated virtual private networks can be used.

To deploy IaaS applications, cloud consumers then install operating system images on the machines as well as their application software. In this type of model, it is the cloud consumer who is responsible for patching and maintenance of the operating systems and application software.

Cloud computing providers typically charge IaaS services on a utility billing computing basis.  For example cost will reflect the amount of resources allocated and consumed.

IaaS refers not to a server or machine that does all the work, but to the facility given to enterprise or business that offers consumers the leverage of extra storage space on servers and data centers.