Waterfall model

Waterfall model

• Sequential execution
• Forward execution with no backward movement to take corrective measures
• Testing happens at the end of the life cycle
• Defects are detected just before making the system live
• Adds lead time due to its late involvement
• Well suited to projects that has low risk in the areas of user interface and performance requirements, but high risk in budget and schedule predictability and control

Advantages

•  Simple and easy to use.
•  Easy to manage due to the rigidity of the model – each phase has specific  deliverables and a review process.
•  Phases are processed and completed one at a time.
•  Works well for smaller projects where requirements are very well understood/stable

 Disadvantages

•  It’s difficult to respond to changing customer requirements.
• Stating all requirements at the beginning of a project is difficult
•  No working software is produced until late during the life cycle.
•  High amounts of risk and uncertainty.
•  Poor model for complex projects.
•  Poor model for long run projects.