Astrocytes are responsible for the structural organization of the neural tissue, for neurogenesis and development of the central nervous system, for generation and maintenance of the blood- and cerebrospinal fluid-brain barriers, for homeostatic maintenance of neurotransmitters and ions, for synaptogenesis and metabolic support, for scavenging of reactive oxygen species and for regulation of local blood flow. Oligodendrocytes provide for the maintenance of interneuronal connectivity. Microglial cells exert multiple trophic effects and are actively involved in shaping the synaptic connections by removing silent or redundant synapses. NG2 cells receive synaptic inputs which might be fundamental for life-long control over myelinating capabilities of the brain tissue. In the periphery, satellite glia, enteric glia and olfactory ensheathing cells oversee various homeostatic functions, whereas Schwann cells support nerve impulse propagation. Homeostatic functions of neuroglia also extend to forming the defense of the nervous system. Every insult to the nerve tissue triggers glial homeostatic response and initiates specific glial defensive reaction. The homeostatic response is primarily neuroprotective. Neurological and psychiatric disorders are, conceptually, failures of such homeostatic responses in which neuroglia display a suboptimal function. Thus, neuroglia are ultimately involved in pathogenesis of many (if not all) brain disorders.