# SaaS, PaaS and IaaS

> Three ways to rent computing, depending on how much of the work you hand over.

- Level: Basic
- Topics: Cloud
- URL: https://tidbit.legios.com.ar/saas-paas-iaas/
- In Spanish: [SaaS, PaaS e IaaS](https://tidbit.legios.com.ar/es/saas-paas-iaas/)

Cloud computing is usually sold in three layers, depending on how much the provider takes care of. With **IaaS** (infrastructure as a service) you rent the raw pieces: virtual machines, disks and networks, like Amazon EC2. The provider runs the data center and the hardware; you install and look after the operating system, the software and everything on top.

With **PaaS** (platform as a service) you hand over more. You bring your code and the platform runs it: it provides the operating system, the runtime and often the database, and handles patching and scaling. Heroku, Google App Engine and AWS Elastic Beanstalk are classic examples. With **SaaS** (software as a service) you rent a finished application and just use it in the browser: Gmail, Slack, Salesforce, Microsoft 365.

The trade-off is always the same: the more the provider manages, the less you can customize and the less work you do yourself. Many services sit between the labels; serverless functions, for example, are often described as a step beyond PaaS. Security responsibility is split the same way: in IaaS you patch your own servers, in SaaS you mostly manage who has access.

## An analogy

Pizza. IaaS is renting a kitchen: you buy ingredients and cook. PaaS is a take-and-bake pizza: it comes ready, you just use your oven. SaaS is eating at the pizzeria: you only choose and enjoy.

## Keep in mind

- IaaS: rent virtual machines, storage and networks; you manage the rest.
- PaaS: bring your code; the platform runs and scales it.
- SaaS: use a finished app, usually in the browser, on a subscription.
- More managed means less work and less control, including on security.

## Go deeper

- [Types of cloud computing (AWS)](https://aws.amazon.com/types-of-cloud-computing/)
- [The NIST definition of cloud computing](https://csrc.nist.gov/pubs/sp/800/145/final)
- [Software as a service on Wikipedia](https://en.wikipedia.org/wiki/Software_as_a_service)

## Related terms

- [Cloud computing](https://tidbit.legios.com.ar/cloud-computing/): Renting computers over the internet instead of buying your own.
- [Virtual machine](https://tidbit.legios.com.ar/virtual-machine/): A complete computer made of software, running inside a real one.
- [Amazon EC2](https://tidbit.legios.com.ar/amazon-ec2/): Virtual computers you rent by the hour, in any size, and switch off when done.
- [Data center](https://tidbit.legios.com.ar/data-center/): A building full of servers where the internet, the cloud and AI actually run.
- [Operating system](https://tidbit.legios.com.ar/operating-system/): The base software that runs a device and lets every app share its hardware.
- [Database](https://tidbit.legios.com.ar/database/): An organized store of data that programs can search and update safely.
- [Google](https://tidbit.legios.com.ar/google/): The search company that gives most products away and makes its money on ads.
- [Web browser](https://tidbit.legios.com.ar/web-browser/): The app that fetches web pages from the internet and draws them on your screen.