What are the essential characteristics of cloud computing?

What will be an ideal response?

The U.S. National Institute of Standards and Technology (NIST) defines cloud computing as having the following essential characteristics: on-demand self-service (consumers can obtain computing capabilities such as server time or network storage as needed automatically on their own); ubiquitous network access (cloud resources can be accessed using standard network and Internet devices, including mobile platforms; location-independent resource pooling): the pooling of computing resources to serve multiple users, with different virtual resources dynamically assigned according to user demand; rapid elasticity (computing resources can be rapidly provisioned, increased, or decreased to meet changing user demand); and measured service (charges for cloud resources are based on the amount of resources actually used).