Cloud Computing

Cloud computing is Internet-based computing,Cloud computing is a general term for anything that involves delivering hosted services over the Internet.These services are broadly divided into three categories:
1. Infrastructure-as-a-Service (IaaS)
2. Platform-as-a-Service (PaaS)
3. Software-as-a-Service (SaaS)

The name cloud computing was inspired by the cloud symbol that’s often used to represent the Internet in flowcharts and diagrams.
Cloud computing describes a new consumption and delivery model for IT services based on the Internet and it typically involves the provision of dynamically scalable and often virtualized resources as a service over the Internet. Most cloud computing infrastructure consists of services delivered through data centers and built on servers.
Clouds often appear as single points of access for all consumers computing needs.

Now lets go towards to the example what is exactly cloud computing is!!!!!.

A simple example of cloud computing is webmail.
Anyone can access their webmail from anywhere in the world simply by knowing the web address of the webmail service, there’s no need to know the name of the server or an ip address or anything else. The webmail provider takes on the job of making sure that there’s enough disk space and processing power to allow all their customers to store and retrieve their mail on demand. The user doesn’t have to worry about maintaining web clients on their PC or, in the case of companies, local email servers.
This is an example of a cloud computing variant known as software as a Service (SaaS) where an application and your data are hosted in the cloud.

There are two other major variants,
Infrastructure as a Service (IaaS),
Platform as a Service (PaaS).

As the names suggest, these variants offer infrastructure or platforms on the web that companies pay to use as and when they need them. Companies can buy time on servers as disk space (IaaS) and deploy their own software and applications on that rented infrastructure. this is  known as IaaS.
PaaS describes buying something more than IaaS in that software is included in the offering. A typical PaaS deployment would be workflow or development platforms which teams use over the internet or a private network to collaborate on projects.

Cloud computing comes into focus only when you think about what IT always needs: a way to increase capacity or add capabilities on the fly without investing in new infrastructure, training new personnel, or licensing new software. Cloud computing encompasses any subscription-based or pay-per-use service that, in real time over the Internet, extends IT’s existing capabilities.