Key definitions of Cloud Computing types

Cloud computing is a style of technology in which data, I.T. resources, and applications are streamed to users "as services" delivered over the Internet.

The key benefits of the cloud computing model include self-service, cost-savings, economies of scale and flexibility.

There are various flavors of cloud delivery models, which encompass private services, public services and a combination of both (hybrid).

There are also new emerging definitions of cloud services being formulated (as we speak) with names like community clouds, cloud streams, mobile clouds and federated clouds.

They all, however, are built on the foundations of virtualisation and the idea that software and infrastructure can be centralised on distant servers and remotely managed and developed via laptops, tablets and Smartphones.


Clouds are typically defined according to three types: private, public and hybrid

Public clouds

Also known as an external cloud, I.T. services are provided "as a service" over the Internet with lesser control over the underlying technology infrastructure. This cloud is appealing to many decision-makers as it reduces complexity and long lead times in testing and deploying new products. It is generally cheaper, too.

Private clouds

Private cloud also offers I.T. activities and functions "as a service" but is a private product for a company or organisation. In this scenario, the private cloud owner shares no resources with outside agencies. Hence, multi-tenancy is not an issue.

Hybrid clouds

This is an integrated approach, combining the power of dedicated servers and public or private clouds. Customised rules and policies govern areas such as security and the underlying infrastructure. In this scenario, activities and tasks are allocated to dedicated servers or cloud servers as required.


While clouds may be private or public, they are also further differentiated at the service-type level. There are broadly speaking three types of dominant services:

Software-as-a-Service (SaaS)

SaaS refers to an end user accessing a remote product or e-commerce service over the Internet. These could include a remote CRM such as Salesforce or a datacentre offered by Amazon Web Services.

Platform-as-a-Service (PaaS)

PaaS is geared towards developers who wish to deploy applications in the cloud and don't want to get involved with the server infrastructure. The Google apps store is just one example of this service.

Infrastructure-as-a-Service (IaaS)

The final version, IaaS, allows developers maximum interaction with the underlying server infrastructure including, but not limited to, deploying back-office applications on that remote environment.


Arguably, the defining moment for virtualisation architecture servers occurred when VMware released its first server products in 2001. VMware dominated the market until Xen hypervisors made its first appearance in 2006 followed by Microsoft's Hyper-V in 2008.

Typically, web hosts such as Virtual Internet use these solutions to virtualise their applications from their x86 Server hardware or software systems thus reducing cost and minimising wasted resources when delivering server capacity that applications need.

These virtualisation solutions leverage:

  • Hypervisors to create virtual machines
  • Shared Operating virtualisation technologies
  • Server virtualisation administrative and embedded management

VMware, Xen, and Hyper-V are expected to dominate the cloud landscape for years to come.

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