A prototype is a rough, early version of a product that is used for testing and development. Prototypes can take many different forms, from low-fidelity paper sketches to high-fidelity digital mockups. The purpose of a prototype is to allow teams to test and refine the product before building the final version. Prototypes are an important tool for product teams, as they allow teams to quickly and cheaply test and iterate on different ideas and design concepts.