Infrastructure-as-a-Service (IaaS) is a cloud computing model where virtual machines are created and used to manage cloud-based information technology and network infrastructure. Organizations can create virtual machines, choose physical host locations, and leverage APIs to manage and configure the cloud-based infrastructure.
The National Institute of Standards and Technology defines Infrastructure-as-a-Service as:
“The capability provided to the consumer to provision processing, storage, networks, as well as other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, and deployed applications; and possibly limited control of select networking components (e.g., host firewalls).”
Infra services over cloud not only constitute services from AWS/Azure/GCP/Other Infra providers, but also entail DevOps tools/processes viz. like Chef, Puppet, GitHub, Jenkins, and Orchestration tools viz. Ansible, Swarm, Kubernetes, Mesos, etc.