Overview:
Cloud computing provides computation, software, data access and storage services that do not require end-user knowledge of the physical location and configuration of the system that delivers the services. Parallels to this concept can be drawn with the electricity grid, wherein end-users consume power without needing to understand the component devices or infrastructure required to provide the service. Cloud computing describes a new supplement, consumption and delivery model for IT services based on Internet protocols and it typically involves provisioning of dynamically scalable and often virtualized resources. It is a byproduct and consequence of the ease-of-access to remote computing sites provided by the internet. This may take the form of web-based tools or applications that users can access and use through a web browser as if the programs were installed locally on their own computers.
But how does it work?
Most websites and server-based applications run on particular computers or servers. What differentiates the cloud from the way those are set up is that the cloud utilizes the resources from the computers as a collective virtual computer, where the applications can run independently from particular computer or server configurations. They are basically floating around in a "cloud of resources", making the hardware less important to how the applications work.
With broadband internet, the need to have the software run on your computer or on a company's site is becoming less and less essential. A lot of the software that people use now-a-days are completely web-based. The cloud takes advantage of that to bring it to the next level.
For example, if you are hosting your website on a local server or from your PC, you must usually select a particular operating system (Windows/Linux/Mac), to determine what software you can run on that particular server. If your site is being hosted in the cloud, there is no need to do that. You can run Windows and Linux programs side by side