Infrastructure-as-a-Service (IaaS) is one of the fundamental cloud computing service models, other two being Software-as-a-Service (SaaS) and Platform-as-a-Service (PaaS). As the name suggests, IaaS provides its clients the computing infrastructure, physical or (quite often) virtual machines and other resources like virtual-machine disk image library, block and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks etc., in a virtualised environment, “the Cloud”, across a public connection, usually the internet.

Physically, the pool of hardware resource is pulled from a multitude of servers and networks usually distributed across numerous data centers, all of which the cloud provider is responsible for maintaining. The client, on the other hand, is given access to the virtualised components in order to build their own IT platforms.

Amazon EC2, Microsoft Azure, Rackspace, Google Compute Engine are among the most popular and highly recognized IaaS providers.

Following are among the main benefits of IaaS to its clients:

• No hardware investment: The underlying physical hardware that supports an IaaS service is set up and maintained by the cloud provider, saving the time and cost of doing so on the client side.
• Scalability: Resource is available as and when the client needs it and, therefore, there are no delays in expanding capacity or the wastage of unused capacity.
• Utility style costing: The service can be accessed on demand and the clients only pay for the resource that they actually use.
• Location independency: The service can usually be accessed from any location as long as there is an internet connection and the security protocol of the cloud allows it.
• No single point of failure: In case of failure of a server or network switch, the broader service would be unaffected due to the remaining multitude of hardware resources and redundancy configurations.