Infrastructure as a Service (IaaS) describes a delivery model of cloud computing services which gives system administrators access to cloud-hosted virtual computers and system primitives used to architect and operate hosted software systems.
IaaS services offer access to virtual computers, network-accessible storage, and network infrastructure components such as firewalls, and configuration services. These software components may be also referred to as "software primitives" or "system primitives."
Usage fees are typically calculated as a function of the time during which computing or networking resources were being utilized as well as the quantity or scale of resource utilization. IaaS providers may also offer value-added services like monitoring and auto-scaling for an additional cost.