Process models: Waterfall, V-model and agile compared

In short: A process model defines the phases in which a project runs; waterfall plans everything upfront, agile models work in short loops with constant feedback.

In more detail: Depending on the project a different model fits. A new building with fixed requirements tolerates other methods than a product whose requirements change constantly.

In Depth

Waterfall model

Phases one after another: requirements → design → implementation → test → operation. Each phase is completed before the next begins. Advantage: clear planning, good documentation, fixed costs with stable requirements. Disadvantage: late changes are expensive, the customer sees nothing running for a long time.

V-model

Extends the waterfall with test levels that face the development phases: requirements ↔ acceptance test, system design ↔ system test, detailed design ↔ integration test, implementation ↔ unit test. Common in safety-critical systems (authorities, medicine, automotive, aviation) with strict evidence.

Iterative and agile

• Spiral model / prototyping: repeated cycles with risk analysis and prototypes.
• Scrum: sprints of 1 to 4 weeks, product backlog, roles (product owner, scrum master, team), reviews and retrospectives.
• Kanban: work visible on a board, limited parallel tasks, continuous flow.
• Extreme programming (XP): pair programming, tests first, small releases. Advantage: fast feedback, flexible. Disadvantage: less predictability, needs a disciplined, self-organised team.

Choice and practice

Ask yourself: are the requirements stable? How critical is an error? How often can the customer give feedback? There are often hybrids (for example agile working within a formal framework). In the IHK project documentation you justify the chosen model and describe how you adapted it.

See also: Agile methods (Scrum, Kanban), Requirements and specification documents, Test pyramid, Network plan and Gantt