The linear model of innovation, also known as the traditional model of innovation, has several synonyms that describe its characteristics and limitations. For instance, it is sometimes referred to as the phases model because it involves a series of stages, from research and development to commercialization and diffusion. It is also known as the funnel model because it assumes that a large number of ideas are generated at the beginning of the process but only a few succeed in the end. Moreover, it is frequently described as a top-down or hierarchical model because it assumes that innovation is driven by experts and institutions rather than users and communities. Finally, it is often contrasted with alternative models that emphasize user-driven or open innovation.