This is the grandfather of other lifecycle models. The project progresses to an orderly sequence of steps. From the initial software concept,down until the final phase. Which is system testing. And at the end of each phase there will be a review to determine wheter the project is ready to advance to the next phase. This model works when there is a stable product definition.
The main advantage of waterfall model is that it allows you to find errors early, but the main disadvantage is that it is not flexible.
