What does the term "waterfall" refer to in software development?

The term "waterfall" in software development refers to a linear project management approach characterized by its sequential phases. In this model, the development process flows in one direction—like a waterfall—through each of the defined stages: requirement gathering, design, implementation, testing, deployment, and maintenance. Each phase must be completed before the next one begins, and there is typically little room for revisiting earlier stages once they are completed. This makes the waterfall model suitable for projects with well-defined requirements and low uncertainty.

The waterfall methodology emphasizes thorough documentation and upfront planning, which can be advantageous in environments where changes are minimal and requirements are clear. This clear structure is beneficial for managing predictable projects but can be less flexible compared to other approaches that allow for iterative development and adaptability.

The other choices refer to concepts that do not align with the characteristics of the waterfall model, such as rapid prototyping or collaborative frameworks, which allow for more flexibility and iterative improvements.