What is the waterfall model in software development?

The waterfall model in software development is a linear, sequential approach where each phase of the development process is completed before the next one begins.

The phases typically include requirements gathering, design, development, testing, deployment, and maintenance. Once a phase is completed, it is generally not revisited, making this model best suited for projects with well-defined, unchanging requirements.

The waterfall model is often used in projects where a clear, upfront understanding of the project's scope is essential. While it provides a structured approach to development, it can be less flexible than agile methodologies, which allow for more iterative and adaptive processes.