Clouds and precipitation are part of a complex Earth system and represent essential components of meteorology, hydrology, and climate. This fact may seem obvious, but it is not. If we want to unambiguously place clouds within the mechanisms of the water cycle, we need to be specific on what is the physics behind their formation, evolution, and dissipation. Once we will have grasped the details of the cloud structure, we will address precipitation in all its countless forms.