What is the Cloud?

Cloud Computing Diagram

Trying to make sense of all the cloud terminology that is being thrown around today can be a daunting task. From the different types of clouds: public, private, external, internal, hybrid, enterprise, etc., to the various types of cloud services: Software-as-a-Service (SaaS), Platform-as-a-Service (PaaS), and Infrastructure-as-a-Service (IaaS) , etc., it’s not easy to understand what each means without exhausting research.

Public vs Private

There are two main types of clouds, public and private, and all other types of clouds fall under these two categories. Public cloud describes services that are available to the general public over the Internet. This service could be a website, an application, a development test bed, or even storage space – it is a resource that is provisioned remotely by the consumer and operated by a third party. Private cloud (also called internal cloud or enterprise cloud) provides the same type of on-demand resources as public, but is deployed within an organization’s internal IT infrastructure, thereby affording higher levels of resilience, governance, and control. The term “external cloud” is a bit more ambiguous. It is sometimes synonymous to the public cloud, but it could also refer to a segment of an organization's private cloud that is hosted externally.

Many small businesses will find public clouds attractive, with its pay-as-you-go fee structure and zero CapEx removing the usual barriers of entry into this technology. Larger companies may find it worth the investment to virtualize their internal infrastructure to garner the benefits of cloud computing while offering much higher levels of control, security, and availability. Hybrid cloud generally refers to architecture that combines heterogeneous environments, ie a physical (non cloud) to virtual (cloud) or internal to external.

Now that we have a clearer understanding of the different types of clouds, we will examine the various cloud services. Public cloud offerings fall under one of these three categories: SaaS, PaaS, and IaaS.

Application Layer (SaaS) - Flickr, Facebook, Gmail
Platform Layer (PaaS) - Google AppEngine, Force.com, Engine Yard
Infrastructure Layer (IaaS) - Winky Networks


SaaS refers to software that is delivered over the Internet as a service on demand. It is the application layer of the cloud. SaaS differs from the traditional method of purchasing software on CD-ROM or downloadable file to be installed locally on the user's computer. SaaS vendors develop and operate software applications for customers to use, but the software is usually run all or in part on the vendor’s hardware – a cloud hosted environment. It is a new software distribution model, one that is inevitably the way all software will be delivered in the future. Sales Force is a prime example of a SaaS offering.


PaaS (also called cloud platform services) is a computing platform and/or solution stack that consumes cloud resources and sustains cloud applications. It is used by developers for the deployment of applications without the cost and complexity of buying and operating the underlying layers that support it. It is an ideal solution for programmers who traditionally have to purchase their own hardware and software to develop, test, and host their applications. PaaS abstracts the infrastructure layer from applications and simplifies collaboration by offering a unified user interface where tracking and testing can be done collectively by the members of the development team. Google AppEngine is one of the most well known PaaS services.


With IaaS, a company’s computing requirements are provided by an outside vendor thereby lowering the company’s CapEx (that is, the money it would have spent purchasing servers, networking equipment, and software) and OpEx (money spent on data center space, maintenance, and management). IaaS makes it possible for startups and small businesses to access IT without upfront investment. It allows a company run more effectively requiring less administration while offering higher levels of performance and reliability. With Winky’s IaaS, your IT infrastructure is created inside our state-of-the-art One Wilshire data center where it is hosted on redundant, top of the line equipment and connected to Tier-1 providers. With instant access to cloud resources, it is simply a better way of delivering IT.

Cloud Computing Chart