Cloud computing can be separated into three distinct categories; Software-as-a-Service, Platform-as-a-Service and Infrastructure-as-a-Service. While these three cloud computing models are very different to one another, to many the differences and the boundaries between them is complex. This post covers the basics of each and how they can be used to benefit businesses.


Software-as-a-Service, which is often referred to as SaaS, is the simplest of these three fundamental cloud models to understand. The majority of us use SaaS services of one type or another, even though we may not realise it. Software-as-a-Service refers to any software that is accessed as a service over the internet. Most email clients are SaaS services, so if you have a Gmail or Hotmail account, for example, you are using a SaaS service. If you are using software as a service you are using a piece of software that is developed by someone else and you are accessing it via the internet through a web browser.

Many enterprises, in fact most enterprises, use cloud-based software, and therefore use a SaaS service. A business many be using many different pieces of software that are hosted in the cloud, which they can then access from anywhere as long as they have an internet connection. The business benefit here is that they can utilise software that has been built by someone else for their own needs. They can access it from anywhere, which is not possible with off-the-shelf software. When using this type of software, though, there isn’t much flexibility. They are using software that has, in most cases, been created to meet the general requirements of large groups of people or organisations – almost built for the masses rather than specifically for a particular user.


Platform-as-a-Service, or PaaS, is where developers have a platform which they can use to build applications. It allows them to create their own applications rather than having to use those created by others (as is the case with Software-as-a-Service). This can include the development of software, websites, mobile apps and social apps amongst others. Tools are provided by the PaaS provider to make this possible. Some developers will create applications that they can then sell, either in the form of mobile apps or packages, such as software. In other cases, developers will be working on behalf of a business to create applications to suit their specific needs.

Businesses can benefit from creating their own applications, as it can be more specific to their requirements than if they are using applications that are already on the market. This increases their flexibility and can make them more productive.


Infrastructure-as-a-Service (IaaS) is the most flexible of these main cloud computing models. An IaaS model is where virtualised hardware, or computing infrastructure, is provided to the IaaS providers’ customers. This includes virtual service space, network connection, bandwidth, IP addresses and load balancers, and these components can then be used by a customer to build their own IT platforms.

As far as a business is concerned, an IaaS service offers great scope so they can create their own IT solutions. The management of the hardware is outsources to the cloud provider, which makes it a cost effective alternative to building IT solutions on hardware they have to purchase themselves.

SaaS, PaaS and IaaS are used for many different purposes and benefit businesses in different ways. With a SaaS service they access software via the internet that has been created by someone else. A PaaS service gives them a platform on which they can create their own applications, while IaaS service allows them to create their own IT solutions. This is much more complex but allows for more flexibility where necessary.


Andrew Marshall ©