The 7 faces of cloud computing

While this buzzword seems to be just about everywhere these days, some vendors and analysts define it narrowly, while others consider it broad enough that anything outside the firewall is a part of cloud computing.

An operational definition "comes into focus only when you think about what IT always needs: a way to increase capacity or add capabilities on the fly without investing in new infrastructure, training new personnel, or licensing new software."

SaaS, utility computing, Web services, platform-as-a-service, they’re among the seven pieces of cloud computing that exist today, even if all are not interconnected.

"Cloud computing might be more accurately described as 'sky computing,' with many isolated clouds of services which IT customers must plug into individually."

Related: Editor's letter: Fuzzy thinking and the Special report: Inside the emerging world of cloud computing.