This document discusses the benefits and proper use of prototyping in web application development projects. Prototyping can improve product quality and return on investment by addressing uncertainties, activating user thinking to communicate needs visually, and finding usability issues early. There are different types of prototypes including horizontal versus vertical and low versus high fidelity. Prototypes should be used to start discussions, help users communicate needs, and reduce costs by implementing changes earlier. Prototyping can be useful regardless of the software development methodology used.