The human nervous system is a complex network that coordinates actions and reactions in the body. It consists of two main parts: the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which connects the CNS to the rest of the body. The nervous system is responsible for processing sensory information, controlling movements, and regulating bodily functions. It uses electrical signals to communicate between neurons, allowing for quick responses to stimuli and maintaining homeostasis within the body.