This document discusses rapid prototyping for web and mobile devices. It begins by defining what a prototype is, as a preliminary model or implementation used to evaluate a design. It then discusses the importance of prototyping, as it allows checking assumptions and minimizing risks. Various prototyping tools are examined, including Keynote/PowerPoint, Axure RP, and Interface 2. Keynote/PowerPoint are easy to use but have limited interactivity, while Axure RP allows more advanced prototyping but costs more. Interface 2 outputs native code but is iOS only. Rapid prototyping is concluded to be important for communicating ideas, saving costs, and enabling agile development, especially for mobile where apps are quickly