Astrocytes are the main glial cell type in the central nervous system. These cells were originally regarded as supportive cells of the brain, but increasing evidence indicates they play fundamental roles in many brain functions, such as: neurotransmitters uptake, energy homoeostasis, neurogenesis, myelination, immunomodulation, neurotrophic factor releasing and blood-brain-barrier maintenance. This book summarises the latest discoveries, from basic to clinical science, regarding the main roles of astrocytes under physiological and pathological circumstances. To ensure that most of readers obtain clear and complete information, all chapters have been written in plain language by worldwide-recognised experts in their respective fields.