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Incremental Model: What It Is and How to Implement It

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When creating a software product, there are a number of software development models—waterfall, Agile, incremental, RAD, iterative, spiral, etc.—to take into account. However, there are several factors to consider when choosing a preferred model. These include the organizational structure, the project’s goals, how it will affect testing methods, and the objectives that must be met. 

In this post, we’ll discuss the incremental development model, a commonly used approach for software development. To start, we’ll discuss its characteristics, benefits, and how it works. Then, we’ll compare this model with the waterfall model in more detail and discuss its advantages and disadvantages. Finally, we’ll look at examples of the incremental model and learn how to implement it. 

What Is the Incremental Model?

The incremental model is a software development methodology that can be used to build large and complex systems. It’s based on the idea of adding new features, or “increments,” to an existing system instead of building the entire thing from scratch at once. 

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In the incremental model, software requirements are divided or broken down into several stand-alone modules or increments in the SDLC (software development life cycle). The incremental development is then carried out in phases once the modules have been divided, encompassing all analysis, design, implementation, necessary testing or verification, and maintenance. Each stage’s functionality is built upon the previously produced functionality, and this process is repeated until the software is finished. 

The incremental model is one in which the development team tries to finish each incremental build as quickly as possible. The goal is to deliver a working product bit by bit. The process includes regular releases, with each release representing an increment in functionality and quality.   

Incremental Model

Types of Incremental Models

There are two types of incremental models in the software development life cycle: 

  • Staged delivery model—In this kind of incremental model, just one section of the project is built at a time. This allows for the product or service to be developed and delivered in stages, with each stage building on the previous one.
  • Parallel delivery model: In this kind of incremental model, different subsystems are built concurrently. It can reduce the time required for the development process as long as there are enough resources available. 

Characteristics of Incremental Models

  • The project is divided into smaller, incremental pieces that are developed and tested individually. As a result, the software will have multiple small subprojects.
  • The final product is not fully developed until the final increment is completed.
  • Each requirement/stage is prioritized, and the one with the highest priority is addressed first.
  • Once the incremented portion is developed, the requirement of a portion is frozen.
  • Each incremental version goes through the phases of analysis, design, coding, and testing. Often, the iterative waterfall model or other methods are used to make each incremental version.

Phases of Incremental Models

The incremental model is an iterative process that helps identify and correct defects early on in the development process. It has four main phases: 

  1. Requirements and analysis—This phase involves gathering and analyzing the requirements of the project, including the scope, objectives, and constraints. This phase also involves defining the overall project plan and identifying the resources needed to complete the project. Once this document has been created, it goes through a series of reviews and revisions before proceeding to the next phase.
  2. Design—In this phase, the project team develops a detailed plan for implementing the project, including the design of the system, the selection of appropriate technologies, and the development of any necessary prototypes or proofs of concept.
  3. Coding and implementation—This phase involves the actual implementation of the project by writing the code according to product requirements. Without using unnecessary hard codes or defaults, the coding standards must be adhered to appropriately to improve and update product quality. This stage also makes it possible to physically execute the designs. 
  4. Test—In this phase, the various components of the system, as well as additional functionality, are checked, integrated, and tested as a whole. After every code implementation, the product should be tested to ensure that it works properly with other pieces of code already written for that project. The system is then deployed to the production environment, where it can be used by end users.

How Incremental Models Work in the SDLC

In the incremental model, the software is divided into different modules that can be developed and delivered incrementally. Since the plan just considers the next increment, there aren’t really any long-term plans throughout this period. This makes it possible to alter a version in order to meet users’ demands.  

During the development life cycle, the development team creates the system’s fundamental components first before adding new functionalities in successive versions. Once these features are successfully implemented, they’re then improved by including new functionality in later editions to increase the functionalities of the product. This process is iterative and follows a waterfall model, with each version building upon the previous one. 

As the software is developed, each new version is delivered to the customer site for testing and feedback, which is taken into account to improve the version.  Once the collection and specification of the requirements are completed, the development process is then separated into different versions. Starting with version 1, each version is developed and then deployed to the client site after each successful increment. 

A Comparison: Incremental vs. Waterfall Models

The waterfall model and the incremental model are the most commonly utilized development models used to improve tracking and develop applications. However, they differ in several ways. The waterfall model is a linear, sequential process where each phase of development must be completed before the next phase can begin. It’s called a “waterfall” model because the development process flows downward in a linear fashion like a waterfall. 

The waterfall model incorporates communication, planning, model construction, production, and deployment in a sequential manner. In contrast, the incremental model is a development process where the product is developed and divided into smaller chunks (increments). These increments are planned, developed, and tested one at a time, and each adds new functionality to the product as it progresses.   

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Some key differences between these models include:

Incremental ModelWaterfall Model
Incurs low costIncurs low cost
Works on small and large teamsWorks on large teams
Is simple to make changes toNot easy to make changes to
Early-stage planning is requiredEarly-stage planning is required
Has a low level of riskHas a high-level risk
Has some possibility for reuseChances of reusability are slim
The client has more influence over the administratorThe administrator has little influence over the client
Testing is carried out following each phase iterationTesting is done when the development phase is finished
It’s possible to go back to an earlier step or phaseNot possible to go back to an earlier step or phase
Operating software requires a short wait timeOperating software requires a lengthy wait time
Uses an iterative frameworkUses a linear framework

Using an Incremental Model

When the incremental model is used in the SDLC, there are greater possibilities of experiencing lower risks and improved project quality. However, here are some additional benefits of this model:  

  • Reduced project risk—When projects are broken down into smaller chunks, it’s easier for teams to understand and manage their risks. Because they’re testing each aspect of their project in stages, they’re more likely to identify risks earlier in the process, so they can take action to reduce or mitigate them. 
  • Improved project quality—When teams are able to test their project in stages, they can find and correct issues before they have a larger impact. Therefore, they’re more likely to produce a high-quality product.
  • Improved project visibility—The incremental model can help teams to improve their project visibility by providing regular milestones to work with. Using these milestones, they can test their progress, identify issues, and adjust their plans accordingly.
  • Improved team collaboration—When teams are able to break down their projects into smaller chunks, they can better manage their resources and dependencies, which can help to improve collaboration across teams.

Pros of the Incremental Model

The incremental model offers many advantages, including the ability to risk-manage progress and increase efficiency. Here are a few other advantages of this approach:   

  • Improved efficiency—The incremental model can help to increase efficiency by allowing teams to plan and organize work more effectively. This approach can also help to reduce the risk of bottlenecks or dependency issues. 
  • Risk-managed progress—Teams can risk-manage progress by testing their project in stages. This means that they can identify and address issues as they emerge and make adjustments as necessary. 
  • Clear reporting and tracking—The incremental model allows teams to clearly report and track their progress, which can help to improve project visibility and collaboration across teams.
  • Feedback is possible— In the incremental model,  the user or the customer can submit feedback at each level to avoid sudden changes.
  • Meeting goals—Once the requirements are mapped out, all software goals and objectives can be satisfied completely through incremental development.

Cons of Incremental Model

The incremental model is not suitable for every project and comes with some inherent risks, including:  

  • This model has to be carefully planned and designed at the beginning, or the entire goal of incrementing will be defeated.
  • There’s a risk that teams will lose focus and their project will become uncoordinated.
  • The iteration stages are rigorous, and they don’t overlap.
  • If teams don’t take time to plan their work and organize their project, they may end up delivering low-quality work and falling behind schedule. 
  • It can lead to wasted effort, as teams may continually have to renegotiate and reprioritize work, which can lead to inefficiencies. 
  • When there’s a problem in one unit, it has to be fixed in all units, which is time-consuming.

When to Use an Incremental Model

The incremental model can be used when: 

  • the objectives of the entire system are clearly stated and recognized, though some details can evolve at each increment over time.
  • there’s a pressing need to get a product to market as soon as possible.
  • the consumer expects the product to be readily available as soon as possible.
  • there’s a need to get a product to the market early.
  • new technology is being deployed.
  • the software team is inexperienced or unskilled.
  • a project’s development timeline is prolonged.
  • there are some high-risk features and goals.
  • there are no resources with the necessary skills.

Example of a Successful Incremental Model

The incremental model is used by leading software companies like WhatsApp, Windows, and MS Office. That’s because, as users, day-to-day needs evolve and so do their demands for better products. Hence, these companies evaluate their needs and repeat the SDLC process. 

Take the case of the Linux operating system. The Linux kernel, which is the core of the operating system, was developed using an incremental approach, with each new version building on the previous one. This allowed the developers to quickly add new features and functionality to the kernel, and to respond quickly to bugs and other issues. As a result, Linux has become a widely used and highly respected operating system that powers many of the world’s computers, servers, and mobile devices. 

Another example is how Microsoft utilizes incremental models to constantly make changes to its products in response to consumer needs. These products come in a variety of versions that are updated as user needs evolve over time. 

Best Practices for Using an Incremental Model

To get the most out of the incremental model, teams should first break down their project into smaller chunks, creating a work breakdown structure (WBS). They should then prioritize their work and decide which activities they’ll perform at which stages. Teams should also create a project plan and decide which activities will take place at each stage, setting realistic expectations and deadlines for different work items. 

Additionally, they should decide when and how often they’ll review their project and report their progress. These reviews are an important opportunity for teams to test their project and make adjustments where necessary. Teams should also take advantage of project management tools and software to help them track their progress and manage their project effectively (e.g., Plutora VSM). To reduce the risks that the incremental model poses, teams should communicate effectively and set realistic expectations for each other. 


Even if there are many models that may create software and achieve the desired goal, we’ve learned in this post that the incremental model achieves the desired goals 100% of the time. We learned that it’s used in the software development life cycle by breaking projects into smaller chunks, which are then developed and tested in stages. This development model also offers many advantages, including the ability to reduce project risk, improve project quality, and increase project efficiency.