Software testing is one of the vital phases of software development since some mistakes might be too costly. Projects developing totally new software are commonly challenged with doubts concerning software requirements as well as realization tools.

As a professional software developer, you spend most of your time working with clients that have very limited knowledge about programming, and most of the time, they cannot fully explain what they actually want you to develop.

This little misunderstanding can cause big troubles. In such cases, it is of utmost importance to constantly communicate and gather information from the customer.

If that happens to you, we recommend you to apply the iterative and incremental software development approach (IID) as it allows swift response to alterations, unlike historical methodologies, such as the waterfall model. 

Therefore, I decided to provide you with some valuable information about the  Iterative-Incremental Development model throughout this article.

So, what is Iterative-Incremental Development approach? 

Defining Interactive-Incremental Development According to Mockus and Herbsleb (2011) Iterative-Incremental Development is one of the methods of Agile software development, extreme programming and rational integrated procedure.

Iterative-incremental model is an approach of software development, which is formed around a steady enhancement in component additions along with a cyclic releases and pattern upgrading.

It starts with planning and carried out through iterative progression cycles that consist of constant customer response and the incremental computation of extra features, finished with the utilization of completed software before moving onto the next cycle (Larman, 2003).

In short, Incremental is a process of adding new components in small pieces whereas the iterative is a process of acting upon the project repetitively, for example, adding new components in cyclic way.

How Does Iterative-Incremental Software Development Work?​

You first have to identify the software requirements, analyze them, and based on your analysis, you design the software and start coding to develop the designed model. Once you are finished, you conduct with the customer, gather feedback and move onto the next software product increment phase or cycle, where you repeat the steps you took at first cycle, but this time you take those steps based on the freshly gathered feedback and information.

The cycle continuous until the end product is perfectly delivered (Larman, 2003).

The perfect examples of iterative-incremental software development approach can be:

• Agile Software Development Model ​
• RAD (Rapid Application Development) Model
• Prototyping -Rational Unified Process 

The Pros and Cons of Applying Iterative-Incremental Development Let’s be real. There is no perfect approach to software development and as all the other application development models, the iterative-incremental software development model also has its pros and cons.

Let’s take a look at the advantages that IID offers:

1. It allows the programmer to develop the prioritized requirements before actually starting the project development.
2. It offers a faster delivery of initial product, and by doing so, it enables the client to acquire the high priority functionalities early.
3. The preliminary delivery cost is rather low.
4. After the completion of each increment (cycle), you can provide the customer with functioning software that he can use until the end product is delivered.
5. You receive a detailed feedback from the customer after the each cycle, so no shockers at the end of the project.
6. Changes in requirements can be accommodated without difficulties, that saves your time and nerves. 

Even though the advantages sound good, a professional programmer should be aware of the following disadvantages of IID:

1. The IID approach requires a careful planning since if you got anything wrong in this phase, you might be forced to start everything all over again.
2. Designing process should also be as efficient as the planning. If you do not ensure addition of the necessary functionality along with provision for modifications during this process, you might find it really hard to continue in later stages of development.
3. Carefully characterized component interfaces are essential since some of the component interfaces are developed earlier than the others. 4.The overall cost of the project might be expensive since you respond to feedbacks you might have to spend more time and resources. 

When to Apply Iterative-Incremental Approach to Software Development? 

The Iterative-Incremental Approach is a great software development method, however, a good programmer should know when to actually apply this approach in practice.

If you are completely new to this approach, here are the suggested occasions when you can actually apply this method in your project:

• When you are provided with all the high-priority functional requirements at the beginning of the project development phase, and expected to progress over time.
• When the initially provided requirements are prioritized, and you know which ones are of high importance and which ones might be changed in later stages of the project -When you are required to provide the customer with basic functioning software even before you completely develop the application
• When you are given a quite lengthy software development timetable that can enable you to reflect on each stage of the development and gather all the information throughout the development phase
• When the project consists of new technology, for example, not everything that’s required in the project are clearly stated or previously done. 

Thus, the product can only be perfectly delivered until going on different cycles of development. Throughout this article, we tried to characterize one of the popular software development methods that widely used in practice nowadays.

Moreover, we decided to include this video tutorial that can help you learn more about Iterative-Incremental Software Development Method:

In this video, the author explains IID approach cycles in great detail.

Conclusion In short​

a constant communication is a fundamental necessity for successful realization of Iterative-Incremental Development method. Particularly uncertainties in the form of shifting requirements may require more communication between the software engineer and client for better understanding and problem solving (Larman, 2003).

Within indecisive working conditions, short iteration phases are required to disclose issues as early as possible. If the iteration cycle is longer, the importance of the communication can be vital for integration part. Without a proper communication and understanding between the parties, it is impossible to successfully implement IID.