The nervous system is a complex network that coordinates the body's activities by transmitting signals between different parts. 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. This system helps regulate functions such as movement, sensation, and reflexes. Nerve cells, or neurons, are the basic units of the nervous system. They communicate through electrical impulses and chemical signals, allowing the body to respond to stimuli. The nervous system also plays a crucial role in maintaining homeostasis, ensuring that internal conditions remain stable despite external changes.