Prototype Model

The Prototype Model builds a working (but limited) version of the software early, shows it to the customer, collects feedback, and refines. It’s ideal when requirements are unclear — instead of writing a spec, you build a draft and iterate.

Steps

1. Gather initial requirements — enough to build a rough prototype.
2. Quick design — focus on visible aspects (UI, navigation, outputs).
3. Build prototype — working model with limited functionality.
4. Customer evaluation — user interacts with the prototype and gives feedback.
5. Refine — incorporate feedback into the next version.
6. Repeat steps 4-5 until the customer approves.
7. Build the final product — use the finalized requirements.

Throwaway vs Evolutionary Prototyping

Aspect	Throwaway	Evolutionary
Purpose	Clarify requirements	Gradually become the final product
Code fate	Discarded after approval	Kept and polished
Speed	Faster	Slower (code must be production-quality)
Risk	Low (you throw it away)	Medium (prototype code might have structural issues)

When Prototyping Helps

• Complex user interfaces (customers must see it to know what they want)
• Web and mobile apps with novel interactions
• Projects where technical feasibility is uncertain
• First-of-its-kind systems