The document describes the waterfall model of software development. It introduces the waterfall model and explains that it is a linear sequential process where each phase must be completed before moving to the next. The phases include requirements analysis, system design, implementation, testing, deployment, and maintenance. While the waterfall model provides structure, it is not suitable for complex or changing projects since changes later in the process are difficult to implement. The model works best for small, well-defined projects where requirements are known upfront.