I believe you're mixing up cloud computing and grid computing. They do, however, have certain characteristics.
Cloud computing is a term that refers to systems in which data is kept over the internet and made available to any online workstation.
Grid computing refers to applications in which a large number of diverse agents work together to tackle sections of the same computer issue in simultaneously. (Consider Seti-at-home or folding-at-home)
However, cloud or grid computing cannot be used to operate current systems in a seamless manner. Both terms relate to architectural structures. There are a few platforms that are generic implementations of these designs, but they're so dissimilar that you can't easily run software that isn't meant to function in a distributed environment on them.
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