Cloud computing (Cloud Computing) cloud computing or the Internet - based process and computer application is used. Cloud computing is an example of Google Apps, which provides business application online using the web browser and can be reached.Servers on the Internet information (applications, web pages, programs and so on) are stored for forever and the user's desktop, notebook, gaming console, etc., are stored temporarily as needed.will get through. Moreover, sequences such as Google through the gears like you got lots of facilities to claim offline.


                          Cloud computing exhibits the following key characteristics:

1. 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. Cloud computing systems typically use REST-based APIs.
2. Cost
 is claimed to be reduced and in a public cloud delivery model capital expenditure is converted to operational expenditure. This is purported to lower barriers to entry, as infrastructure is typically provided by a third-party and does not need to be purchased for one-time or infrequent intensive computing tasks. Pricing on a utility computing basis is fine-grained with usage-based options and fewer IT skills are required for implementation (in-house).[ The e-FISCAL project's state of the art repository contains several articles looking into cost aspects in more detail, most of them concluding that costs savings depend on the type of activities supported and the type of infrastructure available in-house.
3.Device and location independence
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.
4.Virtualization 
Virtualization technology allows servers and storage devices to be shared and utilization be increased. Applications can be easily migrated from one physical server to another.
5.Multitenancy
Multitenancy enables sharing of resources and costs across a large pool of users thus allowing for:
Centralization
Centralization of infrastructure in locations with lower costs (such as real estate, electricity, etc.)
Peak-load capacity increases
Peak-load capacity increases (users need not engineer for highest possible load-levels)
Utilisation and efficiency
Utilisation and efficiency improvements for systems that are often only 10–20% utilised.
6.Reliability
Reliability is improved if multiple redundant sites are used, which makes well-designed cloud computing suitable for business continuity and disaster recovery.
lability and Elasticity
lability and Elasticity via dynamic ("on-demand") provisioning of resources on a fine-grained, self-service basis near real-time, without users having to engineer for peak loads.
7. Performance
Performance is monitored, and consistent and loosely coupled architectures are constructed using web services as the system interface.
8.Security
Security could improve due to centralization of data, increased security-focused resources, etc., but concerns can persist about loss of control over certain sensitive data, and the lack of security for stored kernels. Security is often as good as or better than other traditional systems, in part because providers are able to devote resources to solving security issues that many customers cannot afford. However, the complexity of security is greatly increased when data is distributed over a wider area or greater number of devices and in multi-tenant systems that are being shared by unrelated users. In addition, user access to security audit logs may be difficult or impossible. Private cloud installations are in part motivated by users' desire to retain control over the infrastructure and avoid losing control of information security.
 9. Maintenance
Maintenance of cloud computing applications is easier, because they do not need to be installed on each user's computer and can be accessed from different places.