The nervous system is a complex network that helps our body communicate and respond to the world around us. It consists of two main parts: the central nervous system, which includes the brain and spinal cord, and the peripheral nervous system, which connects the rest of the body to the brain. This system controls everything from our movements to our thoughts and emotions. Nerve cells, or neurons, are the building blocks of the nervous system. They send and receive signals, allowing us to react quickly to changes in our environment. For example, when you touch something hot, your nervous system helps you pull your hand away almost instantly, protecting you from harm.