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What is the Difference Between Agile vs Waterfall?

Before undertaking any development project, the most important decision to make is how to approach the project as a team. Making this decision can get heated due to the two major development methodologies at play. In simple terms, a development methodology determines how the actual work of development is organized and acted on.

The two main development methodologies are the waterfall methodology and the agile methodology. Although technically considered software development, “waterfall” and “agile” are often applied in project management. 

The Waterfall method takes a step-by-step, sequential approach to software development. This means bringing the project from conception to implementation with set steps in-between. This is the traditional approach to software development and is still recommended in some scenarios.

The Agile method is newer than the Waterfall method, but it’s not exactly brand new. This methodology breaks a software development project into incremental stages, slowing building on successive stages with what are called “sprints”.

Both the Waterfall and the Agile methodologies carry their own set of advantages and disadvantages. Overall, both can be beneficial to a software development team. Which one to choose is highly dependent on the project type and circumstances.

What are the differences between Waterfall vs. Agile?

The Waterfall Approach to Development

The Waterfall approach to software development is highly sequential and can be broken down into seven distinct phases. There is a set line of phases, each following the other, that need to be completed one by one. Phase two cannot be started until step one has been completed.

The phases of the Waterfall methodology are:

  • Conception: The idea stage, when developers decide what they want to design and why. This can almost be considered a phase apart from the development project itself since it is necessary for any work to begin.
  • Initiation/Analysis: This stage involves gathering and documenting what the software development project will require – including system and software requirements for the product or project.
  • Design: In this stage, developers determine how they want their piece of software to work and determine which pieces are necessary to code. This phase results in a working software architecture.
  • Construction/Coding: This is the core work of any software development project; after all, it’s the ‘development’ aspect of the project. The stage involves coding each individual unit of the software and testing it along the way, as well as integrating units according to the software architecture from the design phase.
  • Testing: This involves testing the software system-wide; it may include user testing, bug testing, and going back through to fix any specific issues. This needs a very systematic approach.
  • Implementation: In many cases, this means delivering the ‘finished’ product to the customer or rolling out the system-wide software. The stage also means putting a support system in place.

Benefits of the Waterfall Methodology

The Waterfall approach to software has been around for a long time.  With that, there are clearly a number of benefits to the technique.

  • Clear Framework: There is a clear understanding of the project timeline and deliverables before the project actually begins. The full scope of the project is agreed upon by the development team and their customers in advance. This also typically translates into a more carefully designed piece of software.
  • Documentation: Each phase of the process is documented in detail to eliminate any misunderstandings or shortcuts.
  • Flexible Team: It does not always take all of a development team’s time and attention. Depending on the phase, individual team members can focus on other aspects of their work. This essentially allows a more flexible (though less focused) development team.
  • Hands-off Approach: This approach allows for a more hands-off approach from the customer. Once the initial design and project plan is in place, there is little requirement for ongoing customer presence until the review phase.

Potential Drawbacks of the Waterfall Approach

No single approach to software development that will work every time, for every team. There are a few drawbacks to the waterfall approach.

  • Lack of Customer Involvement: While a hands-off approach may work for some end users, it doesn’t always work. Some customers will want more involvement as the project proceeds. If there isn’t a framework for that involvement, the Waterfall approach could lead to frustration on both ends.
  • Changes are Difficult: The whole point of the Waterfall methodology is that it follows clear steps and a set timeframe. Once these elements in place, it can be difficult to make changes once the development team encounters a roadblock. Adaptability is a crucial part of software development to consider, particularly since it can be hard for customers to have a full grasp of the project before it begins. Wireframe or no wireframe, customers cannot always visualize a piece of software before it is implemented.
  • Last-minute Testing: Again, one of the drawbacks of Waterfall vs. Agile is that it is not time bound. While this can often make for an effective project, more often than not development projects start to run behind schedule. For the coding phase, the problem is often stated as “The first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time.” The final testing phase consequently gets rushed, which can lead to very buggy code.
Chart depicting the differences between waterfall and agile

Image via Ganttpro.com

The Agile Approach to Development

The major differences between Agile vs. Waterfall might be summarized by saying that the waterfall approach values planning ahead, while the agile approach values adaptability and involvement.

There are several different flavors of agile development, like Extreme Programming (XP), SCRUM, Kanban, Lean Software Development, Agile Unified Process, etc. But these different methodologies all share some basic characteristics.

The agile methodology has two core elements: teamwork and time. Instead of creating a timeline for one large software development project, Agile breaks the project into individual deliverable pieces. These ‘time-boxed’ phases are called ‘sprints’, and lasts just a few weeks. Once each sprint is completed, the feedback from the previous phase is used to plan the next one. This is the major difference between Agile vs. Waterfall – and the major advantage that Agile offers to developers and team managers alike.

Core Principles of Agile Development

With this team and time-sensitive approach, there are several core principles that any Agile development project will follow.

  • Adaptability: Agile development highlights the importance of being able to change design, architecture, requirements, and deliverables along the way. This is an inherently more flexible approach.
  • Customer Involvement: Because of the constant changes in design and deliverable units, agile software development requires close collaboration between the customer and the development team. This means ensuring customer satisfaction in the early deliverables and continual feedback on deliverables. If the final customer is not available, the product manager as the market expert often takes on the role of the customer.
  • Lean Development: Agile development values making the end product as simple as possible. If the same end result can be achieved with two steps instead of five, Agile development will design the software accordingly. The goal here is to reduce bloat and complexity that can affect performance. In practice, this means finding things that are being done that don’t produce value and eliminating them.
  • Teamwork: As we mention above, Agile values teamwork almost above all else. The development methodology recognizes that no development language is perfect, and no developer can bring everything to the table. Instead, teams must continually assess how they can become more effective and adjust the Agile project as they go. Extreme Programming (living up to its name) insists that developers work in pairs on the principle that two heads are better than one.
  • Time: Agile development takes a very different approach to time during projects, breaking projects into very small units of time. These are the ‘time-boxed sprints’ described above.
  • Sustainability: Instead of pushing for faster deadlines in exchange for an unfinished project, Agile development places value on setting a sustainable pace for software development.
  • Testing: Unlike waterfall approaches where there is a distinct testing phase, Agile approaches insist on testing through every phase of the project. Agile timeframes are shorter than on a traditional project, and continuous testing is built-in as part of the development process. The team needs to provide feedback about project quality on a regular basis.

Benefits of the Agile Methodology

The benefits of agile development have everything to do with customer satisfaction and the end result of the development project. The Agile technique can be an adjustment, but that work may prove worth it for the right development team.

  • Stakeholder Involvement: Taking an Agile approach to development allows – and actually encourages – continuous engagement between the development team and the customer. Ideally, engagement leads to a high level of collaboration, since stakeholders are invited into the process before, during and after every ‘sprint’. This can build trust and result in greater customer satisfaction.
  • Flexible Deliverables: Agile lets stakeholders set deliverables by order of importance, (versus the Waterfall methodology, which has a predetermined process). In other words, if a customer wants to release the basic software before the full suite, this is exactly what agile allows.
  • Adaptability: We mentioned adaptability above as a crucial element of agile development, and it is also one of its major benefits. As customers get a better idea of what they need out of the software, the development can adapt planned sprints accordingly. Since everything is time blocked, adaptation doesn’t mess with the schedules, budgets or requirements of the project.
  • A Higher Quality and User-Friendly Product: Since customers are able to provide feedback after each sprint, products developed using the Agile methodology often end up being very user-friendly. They deliver the value that stakeholders are looking for. More than that, by setting aside time for testing and feedback after each sprint, Agile improves the overall quality of the end product.

Potential Drawbacks of the Agile Approach

Like any single approach to development, Agile may have drawbacks for certain settings or teams. With planning and a dedicated team, these added challenges can be overcome.

  • Required Commitment: Unlike Waterfall, Agile development only works well when the entire development team is committed to the project for the duration. This may be a challenge for some development companies that have a lot going on at once, and may even prove challenging for individual developers.
  • Potential for a Higher Cost and Longer Deadline: While time-boxed sprints allow for planning, it is always possible that some deliverables will not be completed on time. It’s a simple truth of development projects. Creating the necessary additional sprints may mean a higher project cost for the customer.
  • Communication: Since Agile requires a high level of collaboration, development projects using this methodology will also require a high level of communication. For customers and development teams that don’t work in the same physical area, this piece may prove to be an added challenge.

How Do You Make the Choice Between Waterfall and Agile?

Which development methodology you go with – waterfall vs. agile -depends very much on a number of key factors. Waterfall may be best when there is no or limited access to a customer to provide constant feedback. It will best suit projects with a dispersed team and fixed scope and budget.

Agile is more suitable for larger, more complex projects, where there is access to the customer for feedback. Because of the inherent flexibility of the agile approach, it is preferred for projects with constantly changing requirements. 

In recent years, agile development became the predominant product development methodology, being used by a large majority of development organizations. Even those shops still using the waterfall methodology tend to use a hybrid approach using both agile and waterfall. Despite the dramatic success of the agile approach, waterfall is still a valid approach in certain circumstances.

No matter what development methodology you choose, there is a wide selection of project management tools available to you. Be sure to read reviews from real users to help you select the product that’s right for your team.

Brooklin Nash

Brooklin Nash writes about the latest tools and small business trends for TrustRadius. When he’s not writing, you can find him reading YA dystopian fiction (with guilty pleasure) and cooking.

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