The nervous system in the human body is responsible for receiving information, responding to information, and maintaining homeostasis.
The organs of the body that carry out the functions of the nervous system are the brain, the spinal cord, and peripheral nerves (the nerves connecting your brain and spinal cord to the rest of your body).
The nervous system is responsible for allowing you to be aware of the world around you. When information about your surroundings is received it is called a stimulus. Once information about your environment has been received, the nervous system makes it possible for you to respond to your environment. When a change in your environment causes a reaction it is called a response. The nervous system regulates the internal environment in the body. Body temperature, hunger, and oxygen levels are all constantly being maintained by the nervous system.
You're shark diving. A shark is coming straight for you. Your nervous system allows you to process the shark approaching you (stimulus) and help you dodge out of the way (response).