Infrastructure as a service (IaaS) is an instant computing infrastructure, provisioned and managed over the Internet. Quickly scale up and down with demand, and only pay for what you use.
IaaS helps you avoid the expense and complexity of buying and managing your own physical servers and other data center infrastructure. Each resource is offered as a separate service component, and you only need to rent a particular one for as long as you need it. The cloud computing service provider manages the infrastructure, while you purchase, install, configure and manage your own software – operating systems, middleware and applications.