IaaS

IaaS stands for "Infrastructure as a Service". It refers to a usage model or business model in which the infrastructure (network infrastructure and virtual machines) on which systems and applications are built is provided as an Internet service.
Typical services include Amazon Elastic Compute Cloud (Amazon EC2) and Google Compute Engine (GCP).

It is introduced as one of the cloud services that provide services over the Internet, together with Paas (platform provision) and Saas (service and function provision).
SaaS is a form of providing a system developed by a company as a service over the Internet, whereas IaaS provides the infrastructure that users use as a foundation for developing their own systems.