Cloud Computing

Cloud computing is the on-demand delivery of IT resources over the Internet with pay-as-you-go pricing. Instead of buying, owning, and maintaining physical data centers and servers, you can access technology services from a cloud provider like Amazon Web Services (AWS).

Organizations use the cloud for a wide variety of cases, such as data backup, disaster recovery, email, virtual desktops, software development and testing, big data analytics, and customer-facing web applications.

Agility
The cloud gives you easy access to a broad range of technologies so that you can innovate faster and build nearly anything that you can imagine. You can quickly spin up resources as you need them and deploy technology services in a matter of minutes.

Elasticity
With cloud computing, you provision the number of resources that you actually need. You can scale these resources up or down to instantly grow and shrink capacity as your business needs change.

Cost savings
The cloud allows you to trade capital expenses (such as data centers and physical servers) for variable expenses, and only pay for IT as you consume it.

Deploy globally in minutes
With the cloud, you can expand to new geographic regions and deploy globally in minutes. Putting applications in closer proximity to end users reduces latency and improves their experience.

The three main types of cloud computing include Infrastructure as a Service, Platform as a Service, and Software as a Service. Each type of cloud computing provides different levels of control, flexibility, and management so that you can select the right set of services for your needs.  

Infrastructure as a Service (IaaS)
IaaS contains the basic building blocks for cloud IT. It provides access to networking features, computers (virtual or on dedicated hardware), and data storage space. IaaS gives you the highest level of flexibility and management control over your IT resources. 

Platform as a Service (PaaS)
PaaS removes the need for you to manage underlying infrastructure (usually hardware and operating systems) and allows you to focus on the deployment and management of your applications. 

Software as a Service (SaaS)
SaaS provides you with a complete product that is run and managed by the service provider. With a SaaS offering, you don’t have to think about how the service is maintained or how the underlying infrastructure is managed.

Cloud computing tends to shift spending from capital expenditure (CapEx) to operating expenditure (OpEx) as companies buy computing as a service rather than in the form of physical servers. This may allow companies to avoid large increases in IT spending which would traditionally be seen with new projects.

To build a business case for moving systems to the cloud you first need to understand what your existing infrastructure actually costs. You'll also need to calculate the cost of applications -- whether you plan to dump them, completely rebuilding them for the cloud or buying an entirely new SaaS package. The cloud business case also needs to include people costs (often second only to the infrastructure costs) and more nebulous concepts like the benefit of being able to provide new services faster. Any cloud business case should also factor in the potential downsides, including the risk of being locked into one vendor for your tech infrastructure.