Cloud Services For Dummies, IBM Limited Edition  16 PaaS is a cloud delivery option that sits on top of IaaS  to enable companies to take advantage of a unified and  abstracted way of developing and deploying applications.  PaaS hides the complexity of the underlying computing services from IT practitioners in order to streamline the application development life cycle and deployment process. IaaS, the most straightforward of the cloud delivery models, is  the delivery of computing resources in the form of virtualized  operating systems, workload management software, hardware,  networking, and storage services. It may also include the  delivery of operating systems and virtualization technology to  manage the resources. IaaS provides compute power and storage services on  demand. Instead of buying and installing the required  resources in their traditional data center, companies rent  these required resources as needed. This rental model can be implemented behind a company’s firewall or through a  third-party service provider. See more information on renting  in the section “Listing the characteristics of IaaS.” Virtualization  is often used as a foundation of cloud computing. Virtualization separates resources and services from the underlying physical delivery environment. With this approach,  you can create many virtual systems within a single physical  system. A primary driver for virtualization is consolidating  servers, which provides organizations with efficiency and  potential cost savings. IaaS has two types of services: These materials are the copyright of John Wiley & Sons, Inc. and any  dissemination, distribution, or unauthorized use is strictly prohibited. ✓ A  public service  is designed so consumers in any size  business can acquire services in a rental model. Some  public cloud services are open to anyone with a credit  card that pays per use. Other public cloud services are  contractual and provide a higher level of service to the  buyer. Listing the characteristics of IaaS Diving into Infrastructure as a Service