Prototype
A prototype is an early, testable version of a product or feature built to explore and validate ideas, interactions and functionality before full development. It can be a paper sketch, a clickable mockup or partly working code. It exists to answer a specific question cheaply, not to ship, which is why Nielsen Norman Group describes a prototype as a hypothesis: a candidate solution to a design problem.
How Prototypes Work
A prototype simulates enough of the real product to get honest reactions to the part being tested. Nielsen Norman Group describes fidelity along three dimensions:
- Interactivity. From no working links, to a person manually swapping screens in response to the user, to fully clickable navigation and inputs.
- Visuals. From hand-drawn sketches to layouts that look like the finished product.
- Content and navigation. From placeholder text to real content and complete menus.
Low-fidelity prototypes, such as paper prototypes, are fast to make and easy to change between test sessions. A related technique, the Wizard of Oz test, has a person behind the scenes produce the system's responses. High-fidelity prototypes look and respond like the real product, which gives more realistic behavior and lets teams test specific interface details and timing.
The right choice is the lowest fidelity that can answer the question. A navigation structure can be tested on paper. A drag-and-drop interaction usually cannot. AI coding tools now make working code prototypes fast to produce, which is a common use of vibe coding, but a coded prototype is still a learning tool, not production software.
Why Prototypes Matter
Changing a design is cheap before it is built and expensive afterward. Prototypes let teams find out early whether people understand a flow, want a feature or can complete a task, usually through usability testing. They also make ideas concrete: stakeholders react far more usefully to something they can click than to a written description.
When prototyping is fast, scope and direction can change quickly, and the requirements, backlog and agent context need to keep up. See rapid prototyping with vibe coding and keeping product context in sync.
Prototype Example
A team plans to let warehouse managers reorder stock from a mobile app. Before writing production code, a designer builds a clickable prototype of the reorder flow in a design tool, with realistic product names and quantities but no real backend. Five warehouse managers try it on a phone. Most expect to scan a barcode rather than search by name, and several try to change quantities with a swipe that does nothing. The team adds scanning to the design and retests the next week.
Prototype vs. Wireframe vs. MVP
A wireframe is a static layout that shows what goes where on a screen. A prototype is something people can try, to test whether a design or idea works. A minimum viable product (MVP) is a working product released to real customers to test whether the business idea holds. Wireframes often become the starting point for prototypes, and prototypes inform what goes into an MVP.