National Institute of Standards and Technology(NIST) defined Cloud computing  as a model facilitate on-demand globally accessible network to a shared pool of computing resources (e.g., networks, SERVERS, STORAGE, applications, and services) that can be provisioned by self service portal  provided by cloud service provider.

Cloud Computing is a new class of network based computing services that is available over the INTERNET, This model is similar to Utility Computing a collection/group of integrated and networked hardware, software and Internet infrastructure (called a platform).

1. Internet based web service provides hardware, software and networking services to end users
2. These cloud platforms provides simple GUI and APi (Application Programming interface) to access web based computing resources hiding underlying infrastructure details and complexity to end users.
3. In addition, the platform provides on demand services, that are always on, ANYWHERE, anytime and any place.
4. Pay for USE and as on demand, elastic
5. scale up and down in capacity
6. The hardware and software services are available to everyone e.g public, enterprises, corporations and businesses markets