Cloud computing is a technology that uses the Internet and central remote servers to maintain data and applications. Cloud computing allows consumers and businesses to use applications without installation. This technology allows for much more efficient computing by centralizing storage, memory, processing and bandwidth. A simple example of cloud computing is Yahoo email or Gmail etc. You dont need a software or a server to use them. All a consumer would need is just an internet connection and you can start sending emails. The server and email management software is all on the cloud ( internet) and is totally managed by the cloud service provider Yahoo , Google etc. The consumer gets to use the software alone and enjoy the benefits.
The key characteristic of cloud computing is that the computing is "in the cloud" i.e. the processing (and the related data) is not in a specified, known or static place(s). Generally, cloud computing customers do not own the physical infrastructure, instead avoiding capital expenditure by renting usage from a third-party provider. They consume resources as a service and pay only for resources that they use. Cloud computing users avoid capital expenditure (CapEx) on hardware, software, and services when they pay a provider only for what they use. Consumption is usually billed on a utility (resources consumed, like electricity) or subscription (time-based, like a newspaper) basis with little or no upfront cost.
Cloud computing paradigm shift is similar to the displacement of private factory power generators by utility power plants early in the 20th century
pay only for what you use (pay per use),- convert capital expenditure (CapEx) on hardware, software, and services to operating expense,
- low management overhead,
- immediate access to a broad range of applications,
- access systems using a web browser regardless of your location or what device you are using (e.g., PC, mobile).