Today it's a combination of Web hosting, virtualization, and search.
With clouds you don't have to know on which computer your data or software is living, or what operating system you want to run, or how you're going to find what you're looking for.
This last is possible thanks to Doug Cutting. His Java-supported framework, now called Hadoop (after his child's stuffed elephant), has become the lingua franca of cloud computing.
Cutting was inspired by Google's MapReduce and Google File System, but he is now a Yahoo employee. The Hadoop project is hosted by the Apache Foundation.
Hadoop has changed the nature of clouds. What started as a simplified Web hosting or enterprise computing platform has now evolved into a world where everyone can be Google.
As a result most of the Web's biggest players -- Google, Yahoo, Facebook, and Microsoft's new Bing search engine -- are becoming dependent on the little yellow elephant.
When something becomes that important, it's inevitable that intrigue will result. Yahoo made its pitch this week by releasing its own Hadoop implementation, free and open source. This joins versions hosted by Apache, a simplified version used by Facebook, and a commercial version from Cloudera.
Thanks to Hadoop and Cutting Yahoo, which last year was nearly acquired by Microsoft, is suddenly relevant again. It's a player again on the bleeding edge of technology.
Thanks to its ability to manipulate huge data sets in the clouds Hadoop is also the third stage of a rocket that is bringing the Internet, and computing, into a new age. Because what becomes possible for the elephant soon filters down to everyone.
If you're interested in making money in this medium, scale is no longer an object. Huge services can now deliver data instantly, answers coming as fast as you can imagine the question.
Hadoop also offers the final proof, if such were needed, of the power in the open source concept. The Web's largest companies are simultaneously building, and implementing, software you can download free.
Something pleasant to consider over the weekend, while you look up at the clouds.