Prototype Model

What is the Prototype Model?

The Prototype Model is used when the customer knows only the general objectives of the software but not the detailed input, processing, or output requirements. A working prototype is built quickly, shown to the customer, and refined through repeated feedback until it evolves into the final system. This approach is ideal for projects where requirements are ambiguous or likely to change.

Steps in the Prototype Model

• Requirement Gathering: Basic requirements are collected from the customer, even if incomplete.
• Quick Design: A quick, basic design focusing on visible features (like UI) is created — internal design is not detailed yet.
• Build Prototype: A working prototype based on the quick design is developed.
• Customer Evaluation: The prototype is presented to the customer/end users for feedback.
• Refine Prototype: Feedback is used to refine the prototype; this loop repeats until the customer is satisfied.
• Engineer Final Product: Once approved, the prototype is used as a base to build the final, robust system.

Advantages of the Prototype Model

• Users get a real feel of the system early, so missing or misunderstood requirements surface sooner.
• Reduces the risk of building the wrong product, since feedback is continuous.
• Great for projects where requirements are vague or the customer is unsure what they want.
• Encourages active user involvement throughout development.

Disadvantages of the Prototype Model

• Users can start expecting the prototype's quick‑and‑dirty design to work exactly like the final system.
• Can lead to excessive change requests, stretching timelines and cost.
• Developers may take shortcuts to build the prototype fast, which can affect final code quality.
• Extra cost and effort go into a prototype that is often discarded.

When Should Testers Use the Prototype Model?

• When requirements keep changing or are not fully known upfront.
• New, unique products where the customer needs to "see it to believe it".
• Projects with a high degree of user interaction, like UI‑heavy applications.

Understanding when — and when not — to apply the Prototype Model helps testers plan the right test strategy and align testing effort with how the project is actually being built.