IaaS Infrastructure as a Service
Cloud services at the lowest level of abstraction — virtual machines, storage, networking. You manage OS + above yourself. AWS EC2 + S3, GCP Compute Engine, Azure VMs.
Classic pyramid: IaaS (most control, most responsibility) → PaaS → SaaS (least control, least responsibility). Major IaaS providers: AWS, Azure, GCP (hyperscalers), Oracle Cloud, Hetzner, OVH, Digital Ocean. Good for: legacy lift-and-shift, custom workloads, regulatory requirements demanding specific network topology. PaaS saves more time for simple web apps.