By Ed Gubbins

With the possible exception of “net neutrality,” “the cloud” is the most abused technology buzzword of the last few years, applied to almost anything that involves the internet. One of the more troublesome aspects of this phenomenon is the way in which people often refer to “the cloud” as if it’s one thing. It’s not. As cloud computing proliferates and is applied to ever more disparate needs, it will be important for service providers to discern the various segments of the markets and the very different service models that share this term.

Start with what is perhaps the most fundamental and immediate distinction that must be made in any discussion of cloud services: private vs. public. So-called “private clouds” – virtualized environments within an enterprise’s own dedicated data infrastructure – are distinct enough from public clouds – those provided by others using infrastructure that is shared among multiple customers -- that’s it’s difficult to have a meaningful conversation about “the cloud” without first identifying which one of the two you mean. It’s akin to talking about trends

in the restaurant industry and those in your own home kitchen in the same breath; some of the technology may be the same, but the business models and surrounding concerns are night and day. However, that important distinction is somewhat muddied by the fact that most enterprise cloud adopters are taking a hybrid approach – simultaneously developing public and private clouds that, at any given stage, may or may not be directly integrated (at this stage in the technology’s adoption, usually not).

Here’s another key distinction: cloud computing (from here on, I’m talking about the public kind) is sometimes a managed service and sometimes not. Rackspace Hosting, for example, one of

In fact, a lot of enterprise adoption thus far has occurred from the bottom up, without enterprise CIOs knowing about it. Employees need computing resources and don’t want to have to beg IT managers for it, only to be denied because budgets are tight or delayed by bureaucratic roadblocks. So they go to Amazon or Google and purchase IT resources directly, over the web, with a credit card.

Over time, they start talking to their coworkers about how well it went, and the company starts doing more cloud computing. Then they start using it for more important tasks, which requires more reliability and accountability – and in particular, more security. So they begin to talk about the benefits of a more substantive, formal relationship with a cloud provider, and they start asking about managed services.