Iterative vs. Incremental Development: A Comparison

What Is Iterative Development? 

Iterative development is an approach in which IT professionals build up features and functions through repeated cycles or iterations. The product is developed, tested, and then modified based on feedback in each iteration. A new version of the software is released with additional features or improved functionalities. This process is repeated until the final product is completed. 

The main goal of iterative development is to improve the quality of the product by allowing for more in-depth testing and feedback. By developing and testing small parts of the product at a time, it's easier to identify and fix any problems or defects. This can help ensure that the final product is high quality and meets user needs. 

Example of Iterative Development

Imagine a team is building an e-commerce project using an iterative development method. Following this method, the team will implement the primary functionalities of this e-commerce platform in the first iteration. 

That is to say, primary functionalities like the user profiles, items page, shopping carts, favorite, checkout, and customer reviews will be implemented. The first iteration is then developed and tested, and feedback will be collected to refine the product.  

The second iteration will be based on the feedback retrieved from the first iteration. This will help the team decide the features needed in the new version and what they need to discard. 

This process continues until the final product of the site is completely refined and ready for release.

What Is Incremental Development? 

Incremental software development is a method of development in which the product is developed in small, successive parts called increments. Each of these standalone parts goes through the design, functional requirements, execution, and testing cycle. This way, every successive release adds functionality to the prior release until all specified functionality is implemented. The final product can only be delivered at the final stage of the incremental process. 

Example of Incremental Development

Let's assume a team is building the same e-commerce project from before, but this time using an incremental development method. Following this method, they might break the development process down into several sections. These sections include functionalities like user profiles, items page, shopping carts, favorites, checkout, and customer reviews. 

The team implements and releases the first increment, consisting of a complete piece of the user profile and the items page. However, this section will remain incomplete and have no functional capabilities on its own.  

Then, the team implements and releases the second increment, which consists of the shopping carts and checkout. This new increment will build on the previous one and improve on the functional requirements.  

The third increment is finally released with the customer reviews and favorite functionality, which will build on all the previous ones implemented. The team assembles the system tool and inspects it for design flaws, required features, and other significant elements. 

Iterative and Incremental Development in Agile

Agile project management, with the methodology scrum, is closely associated with iterative and incremental development. It encompasses the principles of progressive feature additions, cyclical release, continual experimentation, and feedback loop. 

In agile development, the product is divided into small, manageable chunks called "sprints." At the end of each sprint, a working version of the product is delivered that includes the features developed during that sprint. This allows for frequent feedback and adjustments and helps to ensure that the final product meets the needs of the user.  

This approach is both iterative and incremental. It's iterative because each sprint involves repeating the same process of planning, developing, testing, and evaluating. It's incremental because each sprint builds on the previous one, and at the end of each sprint, a working version of the product is delivered. 

What Is the Difference Between Iterative vs Incremental Development? ​​

Iterative and incremental are both software development approaches that describe how we deliver value throughout a product. The main difference between the two approaches is the way they approach the development process. In an iterative approach, the development process is completed in a series of cycles or iterations. Each iteration involves completing a small portion of the overall project, starting with the most important or critical pieces first. The goal of each iteration is to produce a working version of the software that can be tested and refined after evaluation. 

In contrast, the incremental approach focuses on delivering one complete piece at a time. The first increment is often the core of the product that addresses the basic requirements before supplementary features are added. Every increment builds upon the previous one to produce a working version of the software. 

IterativeIncremental Allows for more flexibility and adaptability even in unforeseen circumstancesLacks flexibility in embracing changeQuickly incorporates feedbackLacks the ability to quickly incorporate feedbackRequires continuous change and improvement to the projectProvides a clear roadmap for completing the project life cycleAids in easy identification of errors after every evaluationTakes time to identify errors since each section is built separately.Has a longer product completion time Has a shorter completion timeDrives more user engagement and feedback Lacks user engagement and feedback until the final product is ready.Becomes costly over time as the development team continuously expands the budget and new features More cost-efficient as the product plan is completely mapped out Progressively transitions from an unpolished product to a high-quality productProduces a higher-quality product after just one release cycle

The Advantages of Iterative Development 

Improved quality: By developing and testing small parts of the product at a time, it's easier to identify and fix any problems, which improves overall product quality. 

Flexibility: Since the product is developed in small, manageable chunks, it's easier to make changes based on feedback.  

Better risk management: In iterative development, risks can be identified and assessed after each product iteration. This way, teams can develop strategies for mitigating those risks, which will help prevent costly delays and problems in the future. 

More frequent feedback: By delivering working versions of the product at regular intervals, iterative development allows for more frequent feedback from users and stakeholders. This can help to ensure that the final product meets the user's needs, and it can also help identify any potential problems or areas for improvement. 

Improved collaboration: Because everyone is involved in the development, testing, and evaluation process, iterative development encourages collaboration between team members and stakeholders. 

The Disadvantages of Iterative Development

Time-Consuming: Iterative development involves repeating the same process multiple times, which can be time-consuming. This can make the development process more lengthy and therefore expensive, which may not be suitable for projects with tight deadlines or budgets. 

Difficult to plan: Since the final product is not fully defined at the start of the project, it can be difficult to plan the development process in an iterative approach. This can make it challenging to estimate the time and resources needed for the project, manage expectations, and set clear goals. 

Challenging to coordinate: There may be many different team members and stakeholders involved in the project. This can make it challenging to coordinate the work of all these parties, which can lead to delays and communication problems. 

Hard to prioritize: Prioritizing the features and requirements of the product may be difficult without a defined plan. This can lead to delays and scope creep as the team tries to balance the needs of the user with the changing requirements of the project. 

Advantages of Incremental Development 

Easy to Manage: Since the incremental development allows the product to be separated into sections, teams can easily manage each chunk of work continuously until completion. 

Saves time: The incremental development method requires you to have a clear vision of what you expect the final product to be and how it functions. This will save a lot of time and allow for early delivery of working software.  

Cost Efficient: With a clearly mapped out plan for the product, your team spends less on expenses as a result of an impromptu change in project scope and functionality. This helps your team save on delivery costs. 

Easy testing and debugging:  Smaller iterations for each section implemented will make it easy to identify possible errors from individual components. It becomes easier to manage risk because risky pieces get identified and handled during every iteration. 

The Disadvantages of Incremental Development

Requires planning: Before the system can be broken down and constructed gradually, it must have a clear and thorough description, which requires a clear vision and goals. 

Rigidity: Because the product is implemented as a separate component, the iteration of each phase is rigid and iterations do not overlap each other. Rectifying an error in one unit necessitates an adjustment in all units, which takes a long time. 

Requires good design: Incremental development needs a suitable strategy and design for how every component comes together to complete the product. This allows developers to focus on one aspect of the software at a time. 

When to Use Iterative Development 

While iterative development has many advantages, it's not the right choice for every project. Iterative development is a good choice when: 

• the goal of a product isn't established in detail and you genuinely want feedback as you refine it

• working on a complex project with high uncertainty 

• a large-scale software project requires a high level of quality and flexibility

• the requirements or goals for your project may change over time

When to Use Incremental Development 

The incremental development may have several benefits, but it's not suitable for all products. It's a useful approach when you: 

• have a clear vision of what you want the product to be

• understand and clearly define your project requirements

• utilize new technologies

• need to develop high-risk features

• don't have a tight deadline or budget

Iterative vs. Incremental: Which Is Right for You?

Between incremental and iterative, there are a number of elements that can influence the decision about which development method to use. Consider these elements: 

Size and Complexity: 

For large, complex projects, an iterative development approach may be the best choice. Iterative development allows the development team to break the project down into smaller, manageable chunks, hence making it easier to focus on one aspect of the project at a time. This can help reduce the overall risk of the project and improve the quality of the software. 

Level of Uncertainty:

If the requirements of the project are not well-defined or are subject to change, an incremental development approach may be the preferred approach. Teams can use it to quickly deliver a working version of the software. They can also refine and extend the functionalities over time in response to changing requirements. 

Resources and Expertise: 

If the development team has limited resources or expertise, an incremental approach may be the best choice. With this approach, the team focuses on one aspect of the project at a time. This can help ensure that each component is thoroughly tested and meets the required standards before moving on to the next component. 

Time to Value: 

The iterative model is often more effective at lowering time to value in the development process. This is because it provides a workable version of the software in the early stages of development. As the product grows, it extends its capabilities over time. This way, the development team can provide value to users and stakeholders more rapidly while also incorporating their input into the development process. 

Iterative vs Incremental Development Conclusion

Ultimately, the choice of which approach to use will depend on the specific goals, circumstances, and requirements of the project. If you wish to develop a product with great quality and cost efficiency, the incremental method may be an ideal option. However, if you're looking for quick output and frequent customer engagement, the iterative approach may be suitable for you. It may be beneficial to use a combination of both approaches in order to take advantage of their respective strengths. 
Check out Plutora for a platform and value stream management system that helps lower the time to value of your software delivery. Plutora offers a wide range of features to improve your software delivery processes, identify errors and bugs, and plan and orchestrate releases. If you want help managing the entire software development lifecycle, including planning, design, development, testing, deployment, and maintenance, give Plutora a try today.