Poll CTOs about game-changing technologies they're watching, and I'll bet the vast majority will put cloud computing at the top of the list. 

While cloud computing isn't yet mature enough to put your entire IT infrastructure on, there is an undeniable paradigm shift in what constitutes a company's "data center".

Below are some frequently asked questions and answers that will get you up-to-speed on the cloud computing revolution. 

I. What is the "cloud"? 

NetworkWorld defines cloud computing as a combination of several existing technologies, including: 

a. Grid computing - multiple commodity servers are tied together to form one big virtual server. If any of the individual nodes fail, the grid remains unaffected and the user is not affected. 

b. Utility computing - metered computing, where you are charged based on usage.  Pay for your computing like you pay for water or electricity. 

c. On-demand computing - most cloud services can be managed from a web interface, and users can provision more or less computing power with the click of a mouse.  This feature is especially useful when you need to temporarily scale up for a big marketing campaign. 

When people talk about cloud computing, they are generally talking about renting cloud services from 3rd party vendors (ie., public clouds).  However, you can also build your own private cloud computing infrastructure in-house to replace separate, individual servers. 

II. So what?  What are the business benefits of cloud computing? 

According to the Open Cloud Manifesto:  

The key characteristics of the cloud are the ability to scale and provision computing power dynamically in a cost efficient way and the ability of the consumer (end user, organization or IT staff) to make the most of that power without having to manage the underlying complexity of the technology. 

This shift from managing individual hardware nodes to managing a cloud means CTOs can spend more time (and money) on strategic, rather than tactical, work.   

As Lew Moorman of Rackspace's Mosso has said: 

Currently businesses spend 75% of their IT budget on maintenance, 25% on strategic activities.  The real promise of cloud computing is inverting that equation. 

Benefits of offloading your IT infrastructure to the cloud has several benefits: 

a. Reduce costs.  By taking advantage of the scale of 3rd party cloud providers, you're sharing the burden and cost of hiring, training, and managing hardware and OS gurus with other customers. 

b. Let someone else deal with the underlying technical details.  Instead of comparing hardware specs and prices for your next round of server purchases, or skimming hundreds of resumes and conducting hours of interviews to hire a crack team of sysadmins, you can worry on big picture issues.  Like where to apply your IT dollars where they can do the most good for your company's bottom line. 

c. Be leaner and more agile.  When you don't have hundreds of your own servers to worry about (and the big team of sysadmins required to keep them running), you also don't have worry about hardware sitting idle or having to layoff IT employees when business slows down. 

III. What can I use the cloud for?