Coming up with a definition for Cloud Computing is getting harder by the minute. I thought I had a pretty good idea what it meant when I first heard the term. The problem is stemming from the fact that everybody wants it to mean something that benefits their interests - the lines are blurring as parties attempt to define it by their specific product, service, or need.

So, how do we sort out this mess and come up with a definition?

Let's begin by looking at the basic meaning of the phrase, apart from what the marketing departments are telling us.

First, "computing" refers to the process of creating output from some set of inputs. When we compute the sum of two numbers, we're performing the exercise of "addition" to come up with an answer. A computer is a machine that takes input (from stored data and possibly a user) and creates some output based on a defined set of rules - we call this a computer program. If you process a set of inputs and generate an output, then you've done computing. It doesn't matter where the black box sits, it's still computing in the purest sense.

So, what is this "cloud" that everybody's talking about then?

When I first got involved in the technical aspects of networking, I remember seeing a "cloud" symbol in graphical diagrams which typically meant "this vague connective space between point A and point B. We knew that information flowed through this vague space whenever it had to get from one place to another. It was the Internet connection between these separate points in space. We didn't care about the cloud because we trusted that it was going to take care of the important details to make sure that the information made it to the destination point. So, the cloud represented the vague but trusted functionality of networking on the Internet. Does it mean that the networking technology had to do anything different than before? Well of course not - we just used the symbol to represent something that we already had but didn't need to care about.

Now, if we apply this idea to cloud computing, we begin to understand it to mean a trusted process of taking inputs and coming up with the required output, but in a way that doesn't require us to think about it. Like the networking black box, it's simply a computing black box, a trusted process where inputs generate outputs in a predictable and repeatable manner. If we have the same set of inputs, we'll get the same set of outputs. Now, instead of the cloud symbol representing the transfer of information between two points, it also includes the transformation of that information into a new output along the way. In fact, the two points could even represent the same point in space but with a new "value" from the transformation.

If we accept this analogy, Cloud Computing is then defined as a repeatable process of transforming information from various inputs to generate an output. How does it work? We don't care as long as it always results in the same output.

Does this mean "cloud computing" includes hosting an application on a server on the Internet? Yes, but it doesn't require it to still be cloud computing. The only requirement is that it be repeatable enough that we don't care how it is done. If we add two numbers together through a service that takes those numbers and generates the correct sum, we don't care where the summation was performed, as long as it comes up with the correct answer. The computing is then represented by a "process cloud" that gives us the correct result, and it can happen on a local computer as well as on an Internet server somewhere else.

So, in the end, cloud computing might involve the Internet, but there's nothing in the definition that strictly requires it. It just means that we don't care where the computing is carried out - it's done somewhere out there in the vague world we know as just a cloud. We can't see into it, and we don't know how it works. We just trust it to always work the same way today, tomorrow, and beyond.