Carry information to the brain, and relay information from the brain to the muscles.

There are three types of basic neurons: sensory, motor and interneurons.
Sensory neurons carry information to the brain, and motor neurons relay information from the brain to the muscles.
The sensory neurons carry messages from sense organs (light, smell, sound, etc.) to the brain, while motor neurons carry messages from the brain to the muscles or glands of the body.