In-depth Explanation Of Iterative and Incremental Development

Relia Software

Relia Software

Duc Toan

Relia Software


Iterative and incremental development (IID) is a project management and software development methodology that combines iterative design with incremental delivery.

iterative and incremental development

Table of Contents

Even the most experienced project managers can feel overwhelmed by problems that were not planned for during the development process. It can cause changing needs and the constant fear of wasting time and money. Iterative and Incremental Development (IID) is a powerful method that can handle these problems well and set the project free to success. 

This is a method for breaking projects into manageable sections, putting user feedback first, and encouraging continuous improvement. In this article, we will show the combination of iterative and incremental concepts including definition, detailed comparisons, implementation guide, benefits, and challenges. Let's check it out!

What is Iterative and Incremental Development (IID)?

Iterative and incremental development (IID) is a project management and software development methodology that combines iterative design with incremental delivery. This approach emphasizes continuous development over multiple cycles, allowing for early user feedback and the ability to make adjustments based on real-world data.

Here is a breakdown of the main concepts:

  • Iterative Design: This involves repeating cycles of planning, creating, testing, and learning. Requirements, design, and development are not fixed at the beginning but are revisited and refined throughout the project. This continuous improvement process helps in adapting to changes and evolving needs. 
  • Incremental Delivery: This breaks the project into smaller, manageable parts. Each increment builds on the previous ones, delivering parts of the project to users for feedback and validation. This approach ensures that functionality is added progressively, allowing for adjustments based on user feedback and ensuring that each part is thoroughly tested and functional.
  • Example: Imagine making a language-learning app. Iterative and incremental development (IID) starts with a basic version with flashcards and quizzes, then gathers user feedback to improve features like spaced repetition or gamified quizzes. This user-centric approach reduces risk, ensures the app meets requirements, and produces a high-quality product.

By integrating these elements, IID encourages a more adaptable and flexible development process, resulting in higher-quality solutions provided faster.

iid definition
What is Iterative and Incremental Development (IID)? (Source: Internet)

Comparison of Iterative and Incremental Development


Both iterative and incremental development strategies share fundamental characteristics that distinguish them from traditional, linear project management approaches. Here is what they have in common:

Continuous Improvement

Iterative and incremental development emphasize continuous improvement throughout the project. They quit the traditional approach, in which the entire project is planned and built in advance, leaving little room for adaptation.

Embrace Feedback and Iteration

Both methodologies emphasize the value of user feedback and iteration. Projects are divided into smaller chunks, allowing for ongoing feedback loops and adjustments based on new data.

Enhanced Flexibility

Both approaches provide more flexibility than traditional methods. They can adjust to changing requirements or market demands as the project progresses.

Risk Management

Both approaches emphasize a proactive approach to risk management. Delivering features in shorter phases reduces the overall risk of the project. If unforeseen challenges arise, the impact is reduced, and changes can be made more quickly.

iterative vs incremental development
Comparison of Iterative and Incremental Development (Source: Internet)


Delivery Focus

This is the key distinction. Iterative development focuses on delivering working functionality in cycles or iterations. The emphasis is on delivering a core set of features early and often, gathering feedback, and then iterating on those features based on that feedback. Incremental development, on the other hand, focuses on delivering the entire project in stages, with each stage adding new functionality to a partially complete product.

User Involvement Level

The level of user involvement is highly emphasized in iterative development. Early user feedback from frequent delivery cycles improves functionality in subsequent iterations. This encourages collaboration and continuous integration of user needs during development.

Meanwhile, in incremental development, user involvement may be minimal. Feedback will be included between stages, but user input is not emphasized throughout development.

Planning and Flexibility

Flexible planning is common in iterative development. User feedback and experiences from previous iterations refine each iteration's details, even with a high-level roadmap. This facilitates project adaptation to changing needs.

In contrast, incremental development planning is more detailed and upfront. Planning each stage with clear functionalities is done beforehand. This approach may be more predictable but less adaptable to major project changes.

Manage Risk

Initial risk identification and mitigation are possible with the iterative approach. By delivering core functionalities early, functionality and user acceptance issues can be identified and addressed before significant investment.

Incremental development presents a more difficult risk management challenge. Issues may not be identified until later, requiring more rework or adaptation.

This table summarizes the key differences:


Iterative Development

Incremental Development


Overall design refinement

Building in functional stages


The entire project progressively improved

Smaller, working functionalities delivered incrementally

Feature Completion

May not be completed in each iteration

Fully functional in each increment

User Involvement Level



User Feedback Integration

Throughout the project

Primarily after each stage delivery

Risk Management

Easier to handle

More challenging

The Combination of Iterative And Incremental Development

Iterative and incremental development (IID) are not simply independent project management methodologies. When combined, they provide an enormous advantage for delivering high-quality projects effectively.

Accelerated Delivery with Reduced Risk

Functional components can be delivered frequently due to the IID iterative function. This allows for early user feedback and testing, making faster discovery and resolution of issues. Meanwhile, incremental development supports this by offering features in smaller, more manageable segments. This can help to lower total risk by limiting investment in possibly incorrect capabilities.

Quality Enhancement

IID's focus on continual feedback processes across iterations promotes project refinement and improvement. Together with the focus on providing core features first of incremental development, this ensures a solid base in the production process. 

In this way of thinking, you build a strong base with core features first, and then you keep making it better by getting feedback from users and iterating. As a result, a high-quality project that goes above and beyond what was expected.

Integrated Flexibility

Both iterative and incremental development are capable of being adaptable. It lets you easily change to new information and add it in, and incremental development keeps you from being stuck with a huge, rigid product.

In general, iterative development provides a framework for continual feedback and change, whereas incremental development ensures that features are given in controlled increments, reducing risk and promoting quality. Together, they provide a dynamic project management style that delivers value early and often, adapts to changing needs, and ensures project success.

When to Use Iterative and Incremental Development?

 Changing Project Needs

Consider making software that users need to modify as they use it. IID is suitable for projects with changing or undetermined requirements. With this flexibility, you can add new information or user comments.  You may improve the software based on real user experience.

 Uncertain Projects

IID protects projects with significant uncertainty about their form or technology stack. Delivering working features in iterations can provide insights and reduce the risk of investing heavily in the wrong direction. Imagine creating a new product in a fast-changing market. IID lets you early-test features with users and adjust based on their feedback.

 Tight Deadlines Projects

For short development cycles, like building a marketing campaign website, IID is a helpful tool. Its focus on regular functioning components makes it excellent for tight timeframes. Putting key features first lets you launch a core product or service quickly. This lets you gather user data for further modification. Consider launching a website with landing pages and forms on time and using user input to improve it.

How to Implement IID in Your Projects?

Step 1: Project Planning

  • Define Project Goals and Scope: Clearly state your project's objectives and deliverables. What problem are you addressing, and what benefits will your project provide (e.g., increased sales, improved customer experience)?
  • Prioritise Features: Identify the core functionalities required for a Minimum Viable Product (MVP). This initial version should be functional and serve as a solid foundation for future iterations. User story mapping is one tool that can help prioritize features.
  • Establish Development Teams and Roles: Form a development team with the necessary skills and expertise. To ensure effective collaboration, clearly define roles and responsibilities (for example, project manager, developer, and tester).

Step 2: Embrace the Iterative Cycle:

  • Develop and Deliver the MVP: Concentrate on implementing the key functionalities identified during the planning stage. This initial version should be fully functional and ready for user testing. Consider Agile project management methods for iterative development.
  • Gather User Feedback: Actively collect user feedback via surveys, interviews, or usability testing tools. This feedback is critical in understanding user needs and identifying areas for improvement.
  • Refine and Iterate: Prioritise and incorporate user feedback into the next iteration. This cycle of building, testing, gathering feedback, and refining is repeated throughout the development process.

Step 3: Incremental Delivery:

  • Plan Development Stages: While iterating on features, consider breaking down the project into stages for incremental delivery. Each stage can deliver a functional product with new features that build on the previous one. This can help to manage stakeholder expectations and demonstrate progress.
  • Manage Dependencies: When using incremental delivery, carefully consider the dependencies between features across stages. Ensure that features planned for later stages do not rely on functionalities that have yet to be developed. A dependency management tool, such as JIRA, can help visualize and manage these dependencies.

Step 4: Communication and Collaboration:

  • Maintain Transparency: Use regular communication tools such as project management software or team chat platforms to keep stakeholders informed throughout the development cycle. This builds trust and ensures that everyone understands the project's goals and progress.
  • Encourage Collaboration: Regular meetings and workshops between development teams, designers, and stakeholders encourage collaboration. Effective communication is critical for a successful IID implementation.

Step 5: Continuous Improvement:

  • Metrics and Monitoring: Set up metrics to track progress and identify areas for improvement. These could include user engagement, defect rates, development velocity (the rate at which features are delivered), and other relevant KPIs.
  • Adapt and Evolve: As the project progresses, be ready to change requirements or market demands. The iterative nature of IID allows for adaptability and continuous improvement.
iterative and incremental software methodology
Iterative and Incremental Development Process (Source: Internet)

>> Read more: 

Following these steps and embracing IID's continual learning nature will put you on track to deliver high-quality projects that satisfy user needs and exceed expectations.

The Benefits of Iterative and Incremental Development

Get Feedback Early and Fix Issues Quickly

IID allows you to get user input early in the process. Issues can be identified and fixed early on, preventing minor issues from becoming major problems and saving time and money in the long run.

Higher Quality and Less Risk

IID breaks down the project into smaller components, each undergoing rigorous testing and improvement. This significantly reduces the risk of undetected issues, leading to a higher-quality product. 

Adaptation and Flexibility

IID supports adaptability by allowing new feedback or data to be easily integrated into subsequent development stages. This flexibility ensures that the project remains relevant and aligned with current needs.

Faster Delivery and Improved Efficiency

IID prioritizes the regular release of functional features, allowing quicker launches of core products or services. This allows for valuable feedback and provides a competitive advantage.

IID benefits
Benefits of Iterative and Incremental Development (Source: Internet)

Challenges of Iterative and Incremental Development

Challenge 1: Scope Creep

In IID, continuously adding new features can lead to scope creep, disrupting the project's timeframe and budget.


  • Define Limits Upfront: Clearly define project scope, prioritize core features, and set change boundaries.
  • Have a Change Plan: Create a procedure for handling requests for new features. Before making any changes, examine the impact on deadlines, budget, and resources.

Challenge 2: Changing Needs

Frequent user feedback can lead to changes in project requirements, causing misunderstandings and extra work.


  • Gather Information: Collect comprehensive initial requirements to create a solid foundation even though IID allows for flexibility.
  • Prioritize and Adapt: Focus on delivering the most essential features first, and adapt to changes while keeping an eye on scope creep.

Challenge 3: Communication 

Effective communication is crucial in IID. Misunderstandings can lead to missed deadlines and user dissatisfaction.


  • Regular Communication: Schedule meetings, distribute progress reports, and conduct user feedback sessions to ensure that everyone is on the same page.
  • Roles and Responsibilities: Clearly define each team member's responsibilities and expectations to avoid confusion.

Challenge 4: Testing Throughout

IID emphasizes the importance of completing thorough testing within each iteration's timeframe. On the one hand, IID's speed and flexibility can be extremely beneficial; however, sacrificing quality through insufficient testing can result in costly rework and dissatisfied users down the road. 


  • Test Early and Often: Test early in the development process and during each iteration (shift-left testing).
  • Focus Your Tests: Prioritize testing the most essential user stories and high-risk features.

>> Read more: Differences Between Functional and Non-Functional Testing

Challenge 5: Deadlines Under Pressure

Despite IID's goal of regular feature delivery, unexpected faults can disrupt project timeframes.


  • Plan Realistically: Set realistic goals and timescales for each iteration, considering your team's capabilities and project complexity.
  • Have a Backup Plan: Create a risk management strategy to identify possible bottlenecks and develop solutions to overcome them.

Understanding these concerns and following the suggestions above will assist you in navigating IID's challenges and realizing its full potential for delivering high-quality projects on time and within budget.

>> Read more: 


Iterative and incremental development (IID) is not a fad. It is a game changer in project management. IID accelerates your time to market, reduces risk, and improves quality by delivering working features early and frequently. It's adaptable to shifting needs and keeps stakeholders satisfied. Consider IID if you value user feedback and continual development in your projects.

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