Editor's note: Thanks to Marco Dini, you can now read this article in Italian.

Right now, in a far off cubicle, someone is designing an e-commerce checkout application. It’s not unusual. There are thousands of existing e-commerce sites with their own checkout applications. And I can bet in the future there will be thousands more.

A checkout application usually has the following elements:

That's it. Six easy steps to executing a purchase -- that's all there is to a checkout application. If it's always that simple, why do we have to continually design new ones? Why can't someone just make an off-the-shelf checkout application that we can plug into any e-commerce site?

We Are All Individuals. Just Like Everyone Else.

Off-the-shelf won't work for a simple reason: every e-commerce business is unique. While the steps will likely be the same, the devil is in the details. More accurately, the devil is in the specific business rules and the customer needs.

Businesses must be unique, even if they are in the same industry, selling similar products. Let me restate that: especially when selling similar products in the same industry. The uniqueness of the business helps customers choose where to buy. Do they want the low cost provider? Or are they the best at delivering service, even at a higher price?

What makes a business unique bleeds into their checkout application. It happens at every step: