The 5G mmWave Channel Model Alliance was formed to take a longer view by addressing issues related to measurement and modeling that impede progress in standards development and hardware optimization. There is a strong link between the modeling and measurement communities. The extent to which the sounder captures the channel’s features will depend on the hardware employed and how well that hardware works, which is why verification is the focus of the first part of this book. The second part of this book describes the main mmWave models that have been presented in the literature, including tapped delay-line stochastic models, geometry-based stochastic channel models, and quasi-deterministic models.