Cloud computing is the on-demand delivery of compute power, database storage, applications, and other IT resources through a cloud services platform via the internet with pay-as-you-go pricing.
Most cloud computing services fall into three broad categories: infrastructure as a service (IaaS), platform as a service (PaaS) and software as a service (SaaS). These are sometimes called the cloud computing stack, because they build on top of one another. Knowing what they are and how they are different makes it easier to accomplish your business goals.
Cloud Computing Categories
Infrastructure as a Service (IaaS)
In this stack, you rent out servers, virtual machines, storage, networks, operating systems from a cloud provider. You can Quickly scale up and down with demand and pay only for what you use.
IaaS helps you avoid the expense and complexity of buying and managing your own physical servers and other data center infrastructure. Each resource is offered as a separate service component and you only need to rent a particular one for as long as you need it. The cloud computing service provider manages the infrastructure, while you purchase, install, configure and manage your own software—operating systems, middle-ware and applications.
Platform as a Service (PaaS)
Platform as a service provides a cloud-based environment with everything required to support the complete lifecycle of building and delivering web-based and mobile applications — without the cost and complexity of buying and managing the underlying hardware, software, provisioning, and hosting.
Like IaaS, PaaS includes infrastructure—servers, storage and networking—but also middleware, development tools, business intelligence (BI) services, database management systems, coding programs and more.
Software as a Service (SaaS)
SaaS Software as a Service refers to end user applications that are run and managed by the cloud service provider. With SaaS, offering you do not have to think about how the service is maintained or how the underlying infrastructure is managed; you only need to think about how you will use that particular piece software. A common example of a SaaS application is web-based email where you can send and receive email without having to manage feature additions to the email product or maintaining the servers and operating systems that the email program is running on.