What is Prototype Model?

The goal of prototyping based development is to counter the first two limitations of the waterfall model.

This prototype is developed based on the currently known requirements. Development of the prototype obviously undergoes design, coding and testing. But each of these phases is not done very formally or thoroughly. By using this prototype, the client can get an "actual feel" of the system.

Advantages

1. It could serve as the first system.
2. Prototyping is an attractive idea for complicated and large systems for which there is no manual  process or existing system to help determining the requirements.
3. The customer doesn’t need to wait long as in the Linear Model.
4. Feedback from customers are received periodically and the changes don’t come as a last minute surprise.
5. Users are actively involved in the development
6. It provides a better system to users, as users have natural tendency to change their mind in specifying requirements and this method of developing systems supports this user tendency.
7. Since in this methodology a working model of the system is provided, the users get a better understanding of the system being developed.
8. Errors can be detected much earlier as the system is mode side by side
9. Quicker user feedback is available leading to better solutions.

Disadvantages

1. Leads to implementing and then repairing way of building systems.
2. Practically, this methodology may increase the complexity of the system as scope of the system may expand beyond original plans.
3. The basic reason for little common use of prototyping is the cost involved in this built-it-twice approach