In watching a Webcast of the iPhone introduction I heard Steve Jobs mention the "cloud" when talking about the new Mobile Me service Apple is rolling out. When he says the data is pushed from the cloud what exactly does that mean?

Apple's new Mobile Me service lets users store files on a server owned or leased by Apple. Those servers are accessed through any Internet connected computer. That's like having a big thumb drive "in the clouds."

The term cloud computing started when network architects started drawing diagrams for their presentations. The architects had symbols for computers and servers and hard drives and switches, but they didn't have a universal symbol that represented "the Internet."

So network architects started using the cloud to represent the Internet in their workflow diagrams.

It became common to talk of pushing data "into the cloud" to represent using the internet to send files to and from servers and Web sites.

As the years passed, Internet-based file storage became a reality when the Internet got fast enough (broadband) and the term "storing files in the cloud" became more common.

Companies like Apple that sell storage "in the cloud" might not even own the storage servers. They can lease the storage from large data centers in more than one place. That way, adding more capacity is quite easy. All those storage facilities can be combined into one "virtual" server that grows as demand dictates.

Users of Google's Google Docs service are really using the cloud. Not only are the files stored on Google's servers, the applications themselves are stored there.

You can open a word processor in your Web browser, create, edit and save the text file and copy it to your computer all without installing any software. It all happens over the Internet "in the cloud."