The nervous system is a complex network of cells and tissues that coordinates and regulates all bodily functions. 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 through nerves. The primary function of the nervous system is to transmit information between different parts of the body, allowing us to sense our environment, move, think, feel emotions, and carry out other essential functions such as digestion and heartbeat regulation.