What is Cloud Computing

 NIST Cloud Computing Definition

After years in the works and 15 drafts, the National Institute of Standards and Technology's (NIST) working definition of cloud computing, the 16th and final definition has been published as The NIST Definition of Cloud Computing (NIST Special Publication 800-145).

Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.

This cloud model is composed of five essential characteristics, three service models, and four deployment models.

 
Link to Download:
The NIST Definition of Cloud Computing


Wikipedia Definition of Cloud Computing:

    Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over a network (typically the Internet). The name comes from the use of a cloud-shaped symbol as an abstraction for the complex infrastructure it contains in system diagrams. Cloud computing entrusts remote services with a user's data, software and computation.

 http://en.wikipedia.org/wiki/Cloud_computing