Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction. It allows users to access applications from anywhere via the internet using web browsers while data and software are stored on remote servers. Some key characteristics of cloud computing include scalability, device and location independence, reliability, and cost reduction by converting capital to operational expenditures. However, privacy, compliance with regulations, security, legal issues, and potential abuse of cloud resources are some concerns associated with cloud computing.

1. Saransh Agarwal
@_saranshagarwal
http://about.me/saranshagarwal
saransh@live.com

2.  It is a technology that provide
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.
 It deliver applications via the internet, which are
accessed from web browsers and desktop and
mobile apps, while the business software and data
are stored on servers at a remote location.

3.  It is a delivery model for IT, the services
based on Internet protocols, and it
typically involves provisioning of dynamically
scalable and often virtualized resources. It
is a by-product and consequence of the
ease-of-access to remote computing sites
provided by the Internet.

4.  The underlying concept of cloud computing dates
back to the 1960s, when John McCarthy opined
that "computation may someday be organised as a
public utility.“
 Almost all the modern-day characteristics of
cloud computing, the comparison to the electricity
industry and the use of public, private, and
community forms, were thoroughly explored in
Douglas Parkhill's 1966 book, “The Challenge of
the Computer Utility”

5.  The actual term "cloud" borrows from
telephony, who until the 1990s offered primarily
dedicated point-to-point data circuits, began
offering Virtual Private Network (VPN) services
with comparable quality of service but at a much
lower cost.
 In early 2008, Eucalyptus became the first open-
source, AWS API-compatible platform for
deploying private clouds. In early 2008,Open
Nebula, enhanced in the RESERVOIR European
Commission-funded project, became the first
open-source software for deploying private and
hybrid clouds, and for the federation of clouds.

7.  Empowerment of end-users of computing resources
by putting the provisioning of those resources in
their own control, as opposed to the control of a
centralized IT service (for example)
 Agility improves with users' ability to re-provision
technological infrastructure resources.
 Application programming interface (API)
accessibility to software that enables machines to
interact with cloud software in the same way the
user interface facilitates interaction between
humans and computers..
 Cost is claimed to be reduced and in a public cloud
delivery model capital expenditure is converted to
operational expenditure.

8.  Device and location independence enable users to
access systems using a web browser regardless of
their location or what device they are using
(e.g., PC, mobile phone). As infrastructure is off-site
(typically provided by a third-party) and accessed via
the Internet, users can connect from anywhere.
 Reliability is improved if multiple redundant sites are
used, which makes well-designed cloud computing
suitable for business continuity and disaster recovery.
 Scalability and Elasticity via dynamic provisioning of
resources on a fine-grained, self-service basis near
real-time, without users having to engineer for peak
loads.

9. • Service Provider makes Resources
• May be free or pay-per-usage modelPublic
• Managed internally or by 3rd party
• Cost spread over few usersCommunity
• Composition of 2 or more clouds
• Data -one deployment system to anotherHybrid
• Operated solely for single organization
• User has to “buy, build and manage”Private

10.  Privacy: The model poses privacy concerns
because the service provider at any point in
time, may access the data that is on the
cloud. They could accidentally or
deliberately alter or even delete some info.
 Compliance: In order to obtain compliance
with regulations including
FISMA, HIPAA, and SOX, users may have
to adopt community or hybrid deployment
modes that are typically more expensive
and may offer restricted benefits.
Issues

11.  Legal: Certain legal issues arise; trademark
infringement, security concerns to the sharing of
propriety data resources.
 Security: Concerns are being voiced about the
security issues introduced through adoption of
this new model.
Solutions to cloud security issues vary, from
cryptography, particularly public key
infrastructure, use of multiple cloud
providers, standardisation of APIs, and improving
virtual machine and legal support.

12.  Sustainability: Although cloud computing is often
assumed to be a form of "green computing", there
is yet no published study to substantiate this
assumption. Energy efficiency can result from
energy-aware scheduling and server consolidation.
 Abuse: Crackers posing as legitimate customers
can purchase the services of cloud computing for
nefarious purposes. This includes password
cracking and launching attacks using the
purchased services.