Cloud by its nature is "on-demand" and includes attributes previously associated with utility and grid models. Grid computing is the ability to harness large collections of independent compute resources to perform large tasks, and utility is metered consumption of IT services, says Kristof Kloeckner, the cloud computing software chief at IBM. The coming together of these attributes is making the cloud today's most "exciting IT delivery paradigm," he says.
Fundamentally, the phrase cloud computing is interchangeable with utility computing, says Nicholas Carr, author of "The Big Switch" and "Does IT Matter?" The word "cloud" doesn't really communicate what cloud computing is, while the word "utility" at least offers a real-world analogy, he says. "However you want to deal with the semantics, I think grid computing, utility computing and cloud computing are all part of the same trend," Carr says.
Carr is not alone in thinking cloud is not the best word to describe today's transition to Web-based IT delivery models. For the enterprise, cloud computing might best be viewed as a series of "online business services," says IDC analyst Frank Gens.