The cerebellum is a small structure of the Central Nervous System that occupies 10% of the total volume of the brain, connecting to the brain and the brainstem through the cerebellar peduncles. Its anatomical division is based on three criteria: midline, fissures, and phylogeny. Based on these criteria, the cerebellum is divided into three layers (granular, Purkinje, and molecular) that are subdivided into subzones or microcomplexes that form the fractured somatotopy or mosaic. Various studies have reported that the anatomy and physiology of the cerebellum have varied throughout evolution in each species, since it has different layers, zones, neurons, interneurons, fibers, deep nuclei, types of glial cells, and lobes in its cortex, which vary depending on the species. For many years, the cerebellum was only classified as a structure related to motor skills (coordination, planning, execution, etc.), but today it is known that it is also involved in sensory, cognitive, emotional, and even autonomic processes. These investigations have expanded the role of the cerebellum in the Nervous System. This review comprises an updated compilation of various investigations on the anatomy and physiology of the cerebellum mainly in humans and rodents.