The Waterfall Model was the first Process Model to be introduced.It is the oldest software lifecycle model and best understood by management . It is used when the requirements are well defined and have low risk .It follows linear process flow. In a waterfall model, each phase must be completed before the next phase can begin and there is no overlapping in the phases.
Advantages:
- Phases are processed and completed one at a time.
- Simple and easy to understand and use
- Works well for smaller projects where requirements are very well understood.
- Clearly defined stages.
- Well understood milestones.
- Easy to arrange tasks.
- Process and results are well documented.
Disadvantages:
- Rarely followed
- difficult for customers to state all requirements explicitly
- requires customer’s patients
- Does not support iterative and leads to blocking states.
- High amounts of risk and uncertainty.
- Not a good model for complex and object-oriented projects.
- It is difficult to measure progress within stages.