Waterfall Model

The most common model of all the models is Waterfall Model.It is more appropriate for small projects and projects for which the software team has very less time to do finish. Since the time is restricted, the requirements provided by the client should be understood to the core.

The main advantage is that, it is very simple and easy to follow.
The main disadvatage is that, there are no feedback. After the s/w team is done with design, they have to move on into implementation and they cannot go back.And also the final product is available only in the end to the user.

The following diagram explains the waterfalol model. As we see it, it is very sequential in flow from one stage to another without any feedback.