Definition
Waterfall
Waterfall is a sequential project management approach where work flows through distinct phases — requirements, design, implementation, testing, deployment — each completed and signed off before the next begins. Plans, scope, and schedule are fixed up front. It suits projects with stable, well-understood requirements but struggles to absorb change discovered mid-project.
Key takeaways
- Waterfall is a sequential approach: requirements, design, implementation, testing, and deployment, each finished before the next begins.
- It fixes scope, plan, and schedule up front, offering predictability for stable, well-understood requirements.
- Its weakness is late feedback — mistakes in early requirements are costly, and mid-project change is hard to absorb.
- Agile (Scrum, Kanban) emerged largely as a response to waterfall's shortcomings for software, favoring short iterations and continuous feedback.
The waterfall model, named for its downward, one-directional flow, treats a project as a linear pipeline. Each phase produces documented deliverables that gate the next, so requirements are frozen before design starts and design is settled before code is written. The appeal is predictability: with everything specified up front, cost, scope, and timeline can be estimated and contracted in advance.
That same rigidity is its weakness. Because feedback arrives only late — typically in testing, after most of the build — mistakes in early requirements are expensive to fix, and changing market needs can't easily be folded back in. Customers often don't see working software until near the end, when course-correction is costly.
Waterfall is not obsolete; it fits domains with fixed, well-understood requirements and high cost of change — regulated, hardware, or construction-adjacent work. Agile methods like Scrum and Kanban emerged largely as a response to its shortcomings for software, favoring short iterations and continuous feedback over a single big plan. Many teams blend the two: a high-level phased plan with iterative delivery inside it.
Planoda supports either rhythm — a fixed milestone-and-Gantt plan for waterfall-style work, or cycles and boards for iterative delivery — on the same schema.
Related terms
- AgileAgile is a family of software-development approaches built on the 2001 Agile Manifesto, which values working software, customer collaboration, and responding to change over rigid plans and documentation. Rather than one process, it is a set of principles — short iterations, continuous feedback, and incremental delivery — that frameworks like Scrum and Kanban put into practice.
- ScrumScrum is an agile framework for delivering work in fixed iterations called sprints. A small cross-functional team plans a sprint, works without mid-sprint scope changes, then inspects and adapts through review and retrospective. Defined roles, events, and artifacts give the framework structure while leaving the actual engineering practices up to the team.
- KanbanKanban is a visual workflow method that maps work onto a board of columns representing stages — typically backlog, in progress, and done. Cards move left to right as work advances. It emphasizes continuous flow, making bottlenecks visible, and limiting work in progress rather than committing to fixed time-boxes.
- Work Breakdown StructureA work breakdown structure (WBS) is a hierarchical decomposition of a project into progressively smaller, deliverable-oriented pieces. The top is the overall outcome; each level below divides it into more concrete components, down to tasks small enough to estimate and assign. It organizes total scope so nothing is forgotten and effort can be rolled up reliably.
- Gantt ChartA Gantt chart is a horizontal bar chart that lays project tasks along a timeline, with each bar's position and length showing when a task starts, how long it lasts, and how it overlaps with others. Dependency lines connect tasks that must happen in order. It is the classic view for planning sequence and seeing a schedule at a glance.