Most people think they have a pretty good idea what "cloud computing" is. From Flickr to Google Calendar, it seems we all make use of the cloud in one way or another.

But researchers at the University of California, Berkeley felt that the meaning of the term "cloud computing," could be clarified.

So, in an effort to define cloud computing and identify the challenges and opportunities it presents, they have posted a white paper, a presentation, and a YouTube video on the topic. And on Thursday, Armando Fox, a professor at Berkeley, presented highlights from the summary, called Above the Clouds, at Berkeley's annualElectrical Engineering and Computer Science Research Symposium.

In essence, Fox said, cloud computing is a utility that gives anyone the access to virtually unlimited, and variable amounts of, computing power on demand. This is to be distinguished, he said, from ideas that have existed for many years such as software-as-a-service, or using hosting services, or remote servers. What's new about cloud computing according to Fox is that Amazon, Google, Microsoft, and others have a working model that provides pay-as-you-go access to utility computing, essentially enabling a single person to design applications that can use thousands of computers at once. (See "The Digital Utility," "Cheap Infrastructure," and "Google's Cloud Looms Large.)

There's still quite of research to be done, Fox assured his colleagues. Some people and companies are reluctant to use a cloud service for fear that they'll be locked into a service provider and won't be able to move their application and data to another provider. This could be solved with standardization across the industry, Fox said. Additionally, people are sometimes hesitant to trust all their data with a single organization. Research needs to be done, he said, to determine the proper approach to privacy.

The report is summarized in a blog post from the Reliable Adaptive Distributed Systems Laboratory at Berkeley.