The nervous system has two major subdivisions—Central nervous system and peripheral nervous system. Central nervous system is that part of the nervous system which occupies the central axis of the body and is enclosed and protected by cranium and spinal column. Peripheral nervous system is the part of nervous system that lies outside the CNS. The histology of CNS has been discussed further in detail. The cerebrum is differentiated into cortex and medulla. The cortex forms the grey matter that envelopes the cerebral hemispheres and consists of nerve cells, fibers and neuroglial cells and are arranged in six layers. Cerebellum is also divided into cortex and medulla. The cerebellar cortex has got three layers. The spinal cord is oval or round in cross-section with white matter outside and gray matter inside. Various types of neuroglia, i.e. oligodendrocytes, astrocytes, microglia, ependymal cells are also discussed with diagrams. Relevant clinical aspect is also discussed.