Cheat Sheet: Cloud computing

Updated: How the hype is becoming a reality...

Do I need an umbrella for my server?
Not quite. Cloud computing is a broad term used to describe technology services delivered over the internet. Rather than companies' running their IT infrastructure inhouse, it is provided remotely via the web, usually on a subscription basis.

Like what?
Cloud computing is made up of three main elements: infrastructure as a service, platform as a service and software as a service.

Infrastructure as a service sees elements such as computer processing power and data storage bought in as online resources, with businesses having access to remote servers to store and process data.

For platform as a service, a range of tools that help developers build and run applications on third-party servers is added.

Cloud computing also encompasses applications delivered over the internet, otherwise known as software as a service or on-demand applications. Software as a service includes applications such as CRM, ERP and office applications.

Any other factors to take into account with cloud computing?
A key part of cloud computing is multi-tenancy, which means cloud providers run applications for different customers simultaneously on the same physical servers. These servers use virtualisation technology to separate the data and processing belonging to each customer.

Scalability - or the ability to increase or decrease the computing resources available to users depending on demand - is another prerequisite of cloud computing. Virtualisation is also a key technology in making this possible as it allows for virtual machines to be rapidly created or switched off.

If physical servers always need to be started up or switched off, the process of adding or removing computing power is much slower and the service is considered to be hosting rather than cloud computing.

So does cloud computing always mean vendors provide everything?
Not necessarily. Another cloud computing option that has emerged is the private cloud.

Public cloud is where a business pays a subscription to access a service run by third-party suppliers - Google Apps and are both examples of this.

Private cloud, on the other hand, is where organisations redesign their IT infrastructure to create a single virtualised environment where resources are pooled for employees to access when they need it.

By doing this, IT departments can divert processing and storage power to wherever...