What Is 'the Cloud'? IaaS, PaaS, and SaaS Explained Simply

What 'the cloud' actually is

Behind the fluffy name, the cloud is simple: instead of buying and running your own servers, you rent computing (processing, storage, databases, apps) from a provider over the internet, paying only for what you use. Those resources live in the provider's massive data centers, Amazon Web Services (AWS), Microsoft Azure, and Google Cloud are the big three. The appeal is that you skip the huge upfront cost and maintenance of physical hardware and can scale up or down instantly.

The pizza analogy

The classic way to understand the three cloud models is 'pizza as a service.' Making pizza at home, you provide everything (the on-premises, do-it-yourself model). With IaaS, someone provides the kitchen and oven, you bring and cook the ingredients. With PaaS, it is like take-and-bake: they handle more, you just finish it. With SaaS, the pizza is delivered ready to eat, you just consume it. As you move from IaaS to SaaS, the provider manages more and you manage less.

IaaS: Infrastructure as a Service

IaaS gives you the raw building blocks, virtual servers, storage, and networking, that you configure and manage yourself. You control the operating system and everything above it; the provider handles the physical hardware and data center. It is the most flexible and the most work. Examples: AWS EC2, Google Compute Engine, Azure Virtual Machines. Use IaaS when you need full control over your environment or are migrating existing systems to the cloud.

PaaS: Platform as a Service

PaaS goes a level higher: the provider manages the servers, operating system, and runtime, so you just deploy your code and let the platform run it. You skip patching servers and configuring infrastructure and focus purely on building your app. Examples: Heroku, Google App Engine, Vercel, and many managed database services. Use PaaS when you want to ship an application fast without babysitting servers, it is the sweet spot for many developers and startups.

SaaS: Software as a Service

SaaS is the cloud most people actually touch: ready-to-use software you access through a browser or app, with the provider handling absolutely everything behind the scenes. You just log in and use it, usually on a subscription. Examples: Gmail, Google Docs, Microsoft 365, Dropbox, Slack, Netflix, and, yes, most modern web apps. Use SaaS when you want a finished tool and have no desire to build or maintain anything, which is most of the time for most people.

Which model, and why it matters

The rule of thumb: SaaS for finished software you just want to use; PaaS for building and deploying your own apps without managing servers; IaaS when you need deep control over the infrastructure. Most organizations use all three at once. Understanding the split matters because it clarifies who is responsible for what, especially security: in every model you are still responsible for your own data and access, even when the provider handles the machines. The cloud did not remove responsibility; it just moved the line.

Related on Skillo

See also: What is Docker? Containers explained, What is Kubernetes? Explained for beginners.

Sources

• Cloud computing service models - Wikipedia

Published date reflects the original event date (2026-05-06). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.