Cloud computing has ben consistently increasing in popularity by taking advantage of third-party computing resources and networks to reduce costs and extend organization’s IT capabilities. It offers effective and innovative ways to deliver software solutions, data storage capabilities and computing services.
The National Institute for Science and Technology (NIST) currently defines four main cloud deployment models including public clouds, private clouds, community clouds and hybrid clouds.
Cloud computing facilitates dynamic and remote control, data storage, memory redundancy, network bandwidth and different specific business services. It provides the capability and flexibility to set-up, change, maintain and deploy computing capacity on-demand.
Public clouds are in general off premise. Physical resources are owned and operated by a third party cloud provider offering their services through the public internet. Services are cost-effective and dynamically provisioned on-demand.
Private clouds are mostly on premise existing either on an enterprise’s local network or are provided through a third party computer service provider. They are characterized by on demand services to a single client including addressing customized security and privacy concerns.
Community clouds are used by specific organizations with shared goals or concerns using the same infrastructure managed by the member organizations or by a third party provider. This model is most suitable for organizations that share common requirements such as security or legal compliance policies.
Hybrid clouds combine features of all of the other cloud models using internal resources in a private cloud to maintain total control over its exclusive and sensitive data and a public cloud for managing and distributing less sensitive information.
The underlying technologies for the cloud deployment models include:

1. Grid computing: This describes a kind of distributed parallel computing which is characterized by processes that are split up to leverage the accessible computing power of multiple CPUs acting together.
2. Utility computing: This is an on-demand, scalable model of acquiring computing capacity, such as CPU, storage and bandwidth from IT service providers.
3. Virtualization: This describes that virtual servers and virtual networks (VNs) offer the on-demand capability to rapidly reconfigure existing resources and provide necessary security stability.

Cloud providers and clients aim for error-free and cost-effective continuous deployment to the cloud. To achieve this, services in Ecommerce, media, finance and social networking are increasingly implementing Agile development methodologies with short release cycles to perform more effectively in a competitive market and to maintain market leadership.