Prototyping fidelity is not a simple scale of quality; it is a strategic choice that shapes what you learn and how quickly. Low-fidelity prototypes (e.g., sketches, wireframes, paper models) trade detail for speed and ambiguity. They are cheap to make and easy to discard, which encourages exploration and reduces attachment to early ideas. Their roughness invites interpretation: stakeholders project their own needs onto simple forms, and teams debate purpose rather than pixels. This makes them most useful when the question is broad (“Should we solve this problem?”) or when the solution space is still wide.

High-fidelity prototypes (e.g., functional code, realistic mock-ups, polished demos) trade speed for specificity. They test detailed interactions, expose technical constraints, and simulate real user experience. Their finish builds confidence in investors and executives who need to see something tangible before committing resources. They are essential when the question is narrow (“Does this interaction work?”) or when validating final aesthetics and performance. The wrong fidelity at the wrong time slows learning: polished prototypes too early anchor you to unproven concepts, while rough prototypes too late fail to reveal critical implementation issues. Match the fidelity to the question you are asking, not to the audience you are showing.