Let us assume that you are the CEO of an organization and you have a big organization. Naturally it becomes your duty to make sure that all employees of your organization have the adequate hardware and software to carry on their tasks. Now, it is not possible to buy software and application for every computer and every employee - as the hiring of employee continues, the buying of licensed product is also mandatory. So you have to spend a lot for each employee.
But there is an alternative concept you can execute for a better result. So instead of buying & installing software for each PCs, load a single application that will allow the employee to log-in to a web-based resource that hosts all the programs for the users based on the requirement. Everything will run by another company's remote servers and facilitates us by providing everything from word-processing applications to spreadsheets, database applications, email, and data analysis programs. This technology is as a whole called the "cloud computing" which brings a revolutionary change in the IT industry.
History of Cloud
At the beginning era of technology, the Client-Server architecture was popular along with the mainframe and terminal application. At that time, storing data in CPU was very expensive and hence the mainframe connected both types of resources and served them to a small client-terminal. With the revolution in the mass storage capacity, the file servers gained the popularity for storing huge amount of information.
In 1990, the giant connecting concept - Internet, finally got enough computers attached to it and the connection of those machines together create a massive, interconnected shared pool of storage that won't be possible by a single organization or institution to afford. There comes the concept of "grid". The term 'grid' has a misinterpretation as a synonym for 'cloud computing' as both of the technology is formed from a lot of computers connected. 'Grid Computing' requires the usage of application programs to divide one large system processing to several thousands of machines. But there lies the disadvantage; that if a single part of a software node fails the processing or working, other pieces of that software nodes may also fail to process. So, this 'grid'-based working concept didn't become so fruitful.
On the other hand, cloud computing involves the concept of 'grid', except that it provides on-demand resource provisioning.
On the first milestone of cloud technology, Salesforce.com engraved its name in 1999. It pioneered the technique of delivering enterprise application via a simple website. They provided both specialist & mainstream software firms to bring up used over the internet.
The next development was in 2002 by Amazon's Web Service (AWS). They provided cloud-oriented services including storage, computing power & human intelligence via Amazon Mechanical Turk. Then in 2006, Amazon launches their EC2 (Elastic Compute Cloud) - a commercial web service that let small organizations and sole proprietors to rent computers on which they run their computer applications.
EC2/S3 became the 1st accessible cloud technology infrastructure service.
In 2009, another big milestone engraved the name of Google with Web 2.0. Google and others started to offer browser-base application via Google apps and other apps. Then came Microsoft's Azure - both Microsoft and Google deliver services in a way that is reliable and easy to consume.