Utility Computing, is also known as on-demand computing, or cloud computing. A Great Definition from wikipedia.org is as follows.

Utility Computing (also known as on-demand computing) is the packaging of computing resources, such as computation and storage, as a metered service similar to a physical public utility (such as electricity, water, natural gas, or telephone network). This system has the advantage of a low or no initial cost to acquire hardware; instead, computational resources are essentially rented. Customers with very large computations or a sudden peak in demand can also avoid the delays that would result from physically acquiring and assembling a large number of computers.

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