In a recent blog post I discussed the "Market / Application Gap." In order for a software product to succeed, it must align with the user's needs. The faster an organization can bridge the gap between the market and the actual application, the greater its competitive advantage and its opportunity for success.

At the start of a project, some effort is given to requirements discovery and this effort varies with software methodology. From here requirements are communicated to engineers who in turn produce an application that reflects the requirement. With agile software development there is an emphasis on taking action as early as possible; waterfall tends to focus on a more complete sets of requirements, designs and test plans (read: more time). With my "Market / Application Gap" diagram in mind, the process looks something like this (order of events, with respect to information flow / deliverables, are numbered):

This cycle represents an iteration: from requirements to delivery of an application. While much has been discussed about the iterative nature of agile development, the truth is that every software process uses iterations. The only question is the length of the iteration. An agile project might have an iteration length of weeks to months; waterfall can have iterations that last years. (Remember, I am defining an iteration in this context as the delivery of an application to the end user.)

At the end of an iteration, the overall gap between the market and the application either grows or shrinks. If you have an iteration cycle of a few months (at most), you can recover if you missed the needs of your market. When you have an iteration cycle of years, you may not get a second chance if you missed the mark. This is one of the core reasons why agile development makes more sense than waterfall: from a risk management point of view it is foolish to take a "big bang" approach where you have few opportunities to satisfy your market.

If the goal is to close the gap between the related participants in the "Market / Application Gap", the quicker you can complete an iteration, the quicker you possibly close the gap. Many successful software products simply work the way users expect; unless you're omnipotent, this requires some trial and error and probably some mistakes. Users will tolerate some mistakes, but won't wait around long. Long iterations can result in a lost audience, which spells doom for commercial software. In my years of software development, I've seen a variety of software processes, many of which claim to encourage iterations and quick feedback. Agile Software Development is the only approach I've seen deliver on this promise in actual practice.