As the name implies, the cerebral cortex forms a shell that covers the brain. In fact, the cortex forms most of the visible surface of the brain. Below its surface is a complex network of neurons and axons. The cerebral cortex is not uniform; rather, it is composed of many structurally and functionally unique subunits that perform a wide range of sensory, motor, and mnemonic processes associated with cognition. Cortex organizes affective behaviors, including responses to painful stimuli, maternal and sexual behaviors, and the expression of rage and other emotions. Like other parts of the CNS, the cerebral cortex does not function in isolation, but it is a part of an intricate plexus of overlapping circuits. This chapter describes the morphology of cortical neurons and the way in which these neurons are assembled into clusters, columns, and areas. In addition, this chapter describes the intrinsic and extrinsic circuitries that subserve the principal functions of the cerebral cortex.