The prototype model involves building a working prototype of the system before full development based on user requirements. It allows users to evaluate early versions of the system and provide feedback to refine requirements. Key steps are gathering requirements, quick design of the prototype, building and refining the prototype based on user evaluations, then developing the full system based on the final prototype. Advantages include early user assessment, improved communication, and reduced risks. Disadvantages include potential delays if multiple prototypes are needed and loss of focus on full system quality.