What Cloud Computing Is
Key to the definition of cloud computing is the “cloud” itself. For our purposes,
the cloud is a large group of interconnected computers. These computers can
be personal computers or network servers; they can be public or private. 
For example, Google hosts a cloud that consists of both smallish PCs and
larger servers. Google’s cloud is a private one (that is, Google owns it) that is
publicly accessible (by Google’s users). 
This cloud of computers extends beyond a single company or enterprise. The
applications and data served by the cloud are available to broad group of
users, cross-enterprise and cross-platform. Access is via the Internet. Any
authorized user can access these docs and apps from any computer over any
Internet connection. And, to the user, the technology and infrastructure
behind the cloud is invisible. It isn’t apparent (and, in most cases doesn’t mat-
ter) whether cloud services are based on HTTP, HTML, XML, JavaScript, or
other specific technologies.
It might help to examine how one of the pioneers of cloud computing,
Google, perceives the topic. From Google’s perspective, there are six key prop-
erties of cloud computing:
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Cloud computing is user-centric. Once you as a user are connected to
the cloud, whatever is stored there—documents, messages, images,
applications, whatever—becomes yours. In addition, not only is the
data yours, but you can also share it with others. In effect, any device
that accesses your data in the cloud also becomes yours. 
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Cloud computing is task-centric. Instead of focusing on the applica-
tion and what it can do, the focus is on what you need done and how
the application can do it for you., Traditional applications—word pro-
cessing, spreadsheets, email, and so on—are becoming less important
than the documents they create.Cloud computing might sound far-fetched, but chances are you’re already
using some cloud applications. If you’re using a web-based email program,
such as Gmail or Hotmail, you’re computing in the cloud. If you’re using a
web-based application such as Google Calendar or Apple MobileMe, you’re
computing in the cloud. If you’re using a file- or photo-sharing site, such as
Flickr or Picasa Web Albums, you’re computing in the cloud. It’s the technol-
ogy of the future, available to use today.
How does cloud computing work? What does cloud computing mean for the
way you use a computer? What are the top cloud computing applications?
Good questions all, and all answered in this book: Cloud Computing: Web-Based
Applications That Change the Way You Work and Collaborate Online. I don’t pre-
tend to answer every question you may have (the overly technical ones in
particular), but I do try to give you a good solid overview of the cloud comput-
ing phenomenon, and introduce you to some of the more popular cloud
applications—in particular, those that facilitate group collaboration.
And that’s where cloud computing really shines. Whether you want to share
photographs with family members, coordinate volunteers for a community
organization, or manage a multifaceted project in a large organization, cloud
computing can help you collaborate and communicate with other group
members. You’ll have a better idea of how this works after you read the book,
but trust me on this one—if you need to collaborate, cloud computing is the
way to do it.