This book reviews the role of glial cells (astrocytes, microglia, oligodendroglia, satellite cells, and Schwann cells) in neuronal health and diseases. It discusses the latest advances in understanding their origin, differentiation, and hemostasis. The book also examines the role of microglial cells in central nervous system (CNS) development, maintenance, and synaptic plasticity. Further, the book presents the functions of astrocytes in healthy CNS and their critical role in CNS disorders, including Parkinson's and Alzheimer's diseases. Notably, the book describes the pathobiology, molecular pathogenesis, stem cells, and imaging characteristics of gliomas. It defines the role of glial cells in regulating iron homeostasis and their effect on the neurodegeneration of neurons. Lastly, it covers the structure, function, and pathology of oligodendrocytes and their role in neuronal health and disease.