Rapid prototyping is a lean development methodology that emphasizes building quick, functional mockups to validate ideas before committing significant resources to full-scale engineering. The goal is to move from concept to testable artifact in days, not weeks. Teams build the minimum viable prototype needed to answer a specific question about user behavior, market fit, or technical feasibility. Prototyping sits at the intersection of design and product strategy. Unlike traditional waterfall design (spec → design → build), prototyping creates a feedback loop: hypothesize → build → test → iterate. This cycle repeats until the core assumption is validated or disproven.