IaaS (Infrastructure as a Service) is a cloud model that provides virtualized compute, storage, and networking on demand, with the customer managing the operating system and everything running on top of it.

What's the difference between IaaS, PaaS, and SaaS?

IaaS gives you raw infrastructure and requires you to manage the OS and up; PaaS additionally manages the runtime and middleware so you just deploy code; SaaS delivers a complete, ready-to-use application with no infrastructure management at all.

What are examples of IaaS?

Amazon EC2, Azure Virtual Machines, and Google Compute Engine are classic IaaS offerings, along with the virtual networking and storage services that accompany them.

Who manages security in IaaS?

Security is shared: the provider secures the physical infrastructure and virtualization layer, while the customer is responsible for OS patching, application security, and network configuration — commonly called the shared responsibility model.

Why would someone choose IaaS over PaaS?

IaaS is preferred when full control over the operating system and stack is required, such as running legacy or highly customized software, or when a lift-and-shift migration needs to happen quickly without redesigning the application.

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Infrastructure as a Service (IaaS)

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Infrastructure as a Service (IaaS) is a cloud computing model that provides virtualized compute, storage, and networking resources on demand, letting customers manage the operating system and everything above it while the provider manages…

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Definition

Infrastructure as a Service (IaaS) is a cloud computing model that provides virtualized compute, storage, and networking resources on demand, letting customers manage the operating system and everything above it while the provider manages the underlying physical hardware.

Overview

IaaS is the most foundational of the three classic cloud service models, alongside Platform as a Service (PaaS) and Software as a Service (SaaS). With IaaS, a provider like AWS, Azure, or Google Cloud rents out raw virtualized infrastructure — virtual machines (like Amazon EC2), block or object storage, and virtual networks — while the customer is responsible for the operating system, runtime, middleware, and application layers on top of it. This gives customers maximum flexibility and control compared to PaaS or SaaS: they can install any operating system, run any software stack, and configure networking exactly as needed, which is why IaaS is the natural landing spot for lift-and-shift cloud migrations of existing applications that weren't built with the cloud in mind. The tradeoff is more operational responsibility — patching operating systems, managing scaling, and configuring security are all left to the customer, whereas PaaS platforms handle much of that automatically. IaaS is typically billed by the hour or second of resource consumption, with discount mechanisms like Reserved Instances and Spot Instances available for predictable or interruptible workloads respectively. Most organizations don't use pure IaaS exclusively — they mix it with PaaS and managed services depending on how much control a given workload actually needs. The AWS Core Services course covers the core IaaS building blocks in depth.

Key Concepts

Virtualized compute (VMs), block/object storage, and networking rented on demand
Customer manages OS, runtime, middleware, and application layers
Provider manages physical hardware, virtualization layer, and data center operations
Usage-based, pay-as-you-go billing with reserved and spot pricing options
Maximum flexibility for running any OS or software stack
Common landing point for lift-and-shift cloud migrations

Use Cases

Lift-and-shift migration of existing applications without redesigning them

Running custom or legacy software stacks that require specific OS configurations

Hosting virtual machines for development, testing, or staging environments

Building custom networking topologies (VPCs, subnets, firewalls) for compliance needs

Providing the underlying compute layer for higher-level platforms and containers

Frequently Asked Questions

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