No one knows for sure as of now what armpit hair is actually for but there must be a good reason we have armpit hair.
It is believed though that Armpit Hair is there to help wick moisture away and to help wick sweat away form our Armpits.
The moisture and sweat being wicked away from our underarms helps aid in ventilation of our skin and underarms and it also helps the odor producing bacteria to be transferred away from the skin.