What is cloud computing?

STREPSIADES: By god, Socrates, tell me, I beg you,
who these women are who sing so solemnly.
Are they some special kind of heroines?

SOCRATES: No—they’re heavenly Clouds, great goddesses
for lazy men—from them we get our thoughts,
our powers of speech, our comprehension,
our gift for fantasy and endless talk,
our power to strike responsive chords in speech
and then rebut opponents’ arguments.
–Aristophanes, The Clouds

Hey! You! Get off of my cloud!
Don’t hang around, ’cause two’s a crowd
On my cloud, baby.
–M. Jagger and K. Richards, “Get Off of My Cloud”

Cloud computing is a long-established concept with a new name. The simple definition is that it involves using Web-based computing tools and storing information on remote servers maintained and operated by another company. This takes the place of traditional computing, where companies bought and ran software on computers they owned — mainframes, minicomputers, or PCs — and stored all of their data on those computers, or on big disk drives.

The cloud concept has been around for years under a variety of labels. It was known as client-server architecture for a while. Corporate enterprises would put all of their data on a central server or series of servers, and then access that data over the Internet through a “thin client,” a terminal or a stripped-down version of a PC that could get you on the Net. Later, the concept was recast as “software as a service.” Again, the idea involved using computers that didn’t have multiple software programs installed, as in the Microsoft vision of the world, but using the Web or the Net to access specific programs, such as salesforce.com‘s customer relationship management suite.

From those permutations we come to cloud computing, which is being offered by various companies in different guises.

The two biggest promoters of cloud computing might be Amazon.com and Google. Both are essentially providing the use of their worldwide server networks, for free or for fees, depending on the level of service (and data storage) you require, along with a set of Web-based tools. Their offerings include Amazon Web Services and Google Apps. The cloud computing concept has attracted a number of computer hardware and software vendors, such as Hewlett-Packard, IBM, Oracle, and SAP. Microsoft will soon unveil something that may or may not be called “Windows Cloud.” Dell tried to trademark the term “cloud computing,” but was denied this year by the US Patent and Trademark Office.

Cloud computing differs from such concepts as autonomic computing, grid computing, and utility computing, although those technologies may be utilized in some cloud computing schemes.

The big question in cloud computing is: Can you trust putting all your data — your family photos, copies of important documents, personal health records, corporate trade secrets and strategic plans — on a computer owned and run by someone else? Will it be secure? Many Web surfers already make that leap of faith in using popular applications like Facebook, Flickr, or Gmail. Richard Stallman of the Free Software Foundation recently inveighed against the idea of trusting any for-profit corporation, even Google, to safeguard your information.

In short, it’s going to take a significant conceptual leap to go from keeping everything on your PC or in your corporate data center to putting everything on the computers and networks of a trustworthy third party.