Cloud Service Models: IaaS, PaaS & SaaS

Instructor: Beth Hendricks

Beth holds a master's degree in integrated marketing communications, and has worked in journalism and marketing throughout her career.

Cloud service models come in three types: Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS). In this lesson, you'll learn more about each and what they do.

In The Clouds

Jamie is anticipating a busy work day ahead. She logs into her company's virtual computing environment on Amazon EC2 and navigates to her calendar on Microsoft Office 365 through the cloud-based Windows Azure. And, she does all of this from the comfort of her home office while maintaining full accessibility to all of her company's systems and applications.

Various cloud computing models exist to serve different business needs.
cloud, computing, models, service, iaas, paas, saas

Confused yet? Cloud computing, an internet-based approach to accessing programs, software and files from anywhere in the world with an internet connection, is the 21st century's version of computer convenience and accessibility. Where once you had to travel to a college campus, for example, to access its computer network, today's students can log into that network from home or from a coffee shop.

Since there are many things that can be done ''in the cloud,'' there are three different cloud service models that providers have developed. Each service represents a different role and offers services to fulfill that role. Let's take a closer look.

Types of Cloud Service Models

Think of cloud service models like cake. Yes, cake! There are three different ways for you to get that cake you've been craving:

  1. You can go to the store and buy all of the individual ingredients, mix them together and bake them. This is like Infrastructure as a Service.
  2. You could go to the store, buy a box cake mix where all of the ingredients have been pre-measured and pre-mixed for you, stir it up and bake. This is like Platform as a Service.
  3. The final option is just to go to a bakery and buy a cake that has already been baked and frosted so you can dig in. This is like Software as a Service.

Here you see three different approaches to getting cake. Each of these is also representative of a type of service model used in cloud computing. Read on to learn more about each one.


Think of IaaS, or Infrastructure as a Service, as the foundation of cloud service. Thus, it is the most important level because it is the base that helps power everything else. IaaS does not include an operating system or any software applications, but serves as the infrastructure that supports these systems and programs.

IaaS can include virtual computers, storage capacity, virtual networks, firewalls and much more. For example, if you need email service for your business, you might choose to implement IaaS from a cloud service provider that you can use to host and run any email application of your choosing. Infrastructure as a Service lays the groundwork for hosting hardware, software, storage and other applications chosen by the customer.

Without IaaS, there is nowhere for the resources we'll see in PaaS and SaaS to live.


PaaS, or Platform as a Service, includes programs and operating systems that can be hosted on a company's infrastructure. Sometimes called ''middleware'' because it resides on IaaS to enable software delivery, Platform as a Service helps computer users develop and run their programs and applications.

For example, Google's App Engine is a PaaS that allows software developers a space where they can build and run software. For a company's email service, PaaS provides the space on which the email application of your choosing can run, while handling the hardware necessary in the background. In this way, PaaS is a host for the software selected in the SaaS category.

With PaaS, consumers don't have to worry about managing the operating system or other platform services, and can instead focus on the actual software application they need.

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