IaaS, PaaS and SaaS

Introduction

Cloud providers offer services at different levels. The main question is: how much do you want to manage yourself, and how much should the provider handle?

The simple explanation

IaaS gives you the building blocks, PaaS gives you a place to build, and SaaS gives you the finished product.

Think about eating pizza:

Make it at home is like owning your own servers. You do everything.
IaaS is like renting a kitchen. You bring the ingredients and cook.
PaaS is like a takeaway where you choose the toppings. You focus on your recipe.
SaaS is like eating at a restaurant. The meal arrives ready.

Infrastructure as a Service (IaaS)

You rent basic computing resources: virtual servers, storage and networks. You install and manage the operating system and your software. You get lots of control, and lots of responsibility.

Examples: Amazon EC2, Azure Virtual Machines, Google Compute Engine.

Platform as a Service (PaaS)

The provider runs the servers and operating system. You upload your code and it runs. You manage your application and data, not the machines.

Examples: Heroku, Google App Engine, Azure App Service. Hosting services such as Netlify also remove server work for websites.

Software as a Service (SaaS)

You use a finished application through a browser or app. The provider runs everything. You manage only your own settings and data.

Examples: Gmail, Google Docs, Microsoft 365, Slack.

Quick quiz

Your team wants to use an online tool for email and documents without managing any servers. Which model is this?

Serverless

You may also hear serverless. It does not mean there are no servers. It means you do not manage them. You write small functions, and the provider runs them only when needed and bills for the time they run.

Try it yourself

Think of three tools you use. Decide whether each is IaaS, PaaS or SaaS, and who looks after updates and security in each case.

Summary

IaaS is rented infrastructure, PaaS is a platform for your code, SaaS is a finished app.
Moving from IaaS to SaaS, you manage less and the provider manages more.
Serverless means you do not manage servers, and you pay for the work done.