The Infrastructure as a Service (IaaS) cloud computing model enables automated deployment of compute, storage, networking, and networking services. Using this cloud mode, users can build a virtual data center in the cloud with as many resource capabilities as found in traditional data centers. In addition, users can create their private data centers in the cloud and establish a VPN connectivity with their local data centers.

IaaS also provides Application Programming Interfaces (APIs) for software developers to access cloud resources programmatically.

Thus, users don't have to invest in hardware and are able to leverage the cloud resources and then be billed based on consumption. Cloud providers such as Amazon (AWS), Microsoft (Azure), Google (GCP), and so on, are examples of companies that provide IaaS.

The following diagram summarizes the differences between IaaS, PaaS, and SaaS:

As shown here, in traditional software deployments, the entire stack is managed by the organization that implements the system. IaaS reduces the burden of managing the Networking, Storage, Servers, and Virtualization layers by owning and managing them. Thus, the user no longer has to worry about these layers and can focus on the software applications.

PaaS further relieves the user from managing the Operating System, Middleware and Runtime layers, thus leaving only the application management and data management responsibilities to the user.

Finally, a SaaS provider will own and manage the entire stack and the user just has to log in to the host to perform their activities.