Cloud Computing:Hot trend in computer field.

Cloud computing is a colloquial expression used to describe a variety of different 

typesof computing concepts that involve a large number of computers connected 

through a real-time communication network (typically the Internet).Cloud computing 

is a jargon term[citation needed] without a commonly accepted non-ambiguous
scientific or technical definition. In science, cloud computing is a synonym for
distributed computing over a network and means the ability to run a program on
many connected computers at the same time. The phrase is also, more commonly
used to refer to network-based services which appear to be provided by real
server hardware, which in fact are served up by virtual hardware, simulated by
software running on one or more real machines. Such virtual servers do not
physically exist and can therefore be moved around and scaled up (or down)
on the fly without affecting the end user - arguably, rather like a cloud.

The popularity of the term can be attributed to its use in marketing to sell hosted
services in the sense of application service provisioning that run client server
software on a remote location.

Advantages:-

Cloud computing relies on sharing of resources to achieve coherence and
economies of scale similar to a utility (like the electricity grid) over a network.
At the foundation of cloud computing is the broader concept of converged
infrastructure and shared services.The cloud also focuses on maximizing the
effectiveness of the shared resources. Cloud resources are usually not only
shared by multiple users but as dynamically re-allocated per demand. This
can work for allocating resources to users. For example, a cloud computer 

facility, which serves European users during European business hours with a
specific application (e.g. email) while the same resources are getting reall-
ocated and serve North American users during North America's business
hours with another application (e.g. web server). This approach should
maximize the use of computing powers thus environmental damage as well
since less power, air conditioning, rackspace, etc. is required for a variety
of functions.

The term "moving to cloud" also refers to an organization moving away from a 

traditional CAPEX model (buy the dedicated hardware and depreciate it over
a period of time) to the OPEX model (use a shared cloud infrastructure and
pay as you use it).Proponents claim that cloud computing allows companies to
avoid upfront infrastructure costs, and focus on projects that differentiate their
businesses instead of infrastructure.Proponents also claim that cloud computing
allows enterprises to get their applications up and running faster, with improved
manageability and less maintenance, and enables IT to more rapidly adjust
resources to meet fluctuating and unpredictable business demand.