The brain is the most complex organ in the body. It contains over 100 billion specialized nerve cells called neurons, which communicate with each other through electrical signals (nerve impulses).
If you could line up all the neurons in your body end to end, they would stretch from Earth to the moon.
Neurons make up only 10% of brain cells. The other 90%, called glial cells, help the neurons send signals to the rest of the body to control movement, thought processes, perceptions, and speech.