The term co-wash is used to describe a way to cleanse your hair without the use of shampoos. Many naturals opt out of using shampoo to wash their hair because it dries out their hair too much, by eliminating any of the natural oils made from the scalp. Washing with shampoo can also strip the hair of it's natural sheen and color. I've been co-washing my hair all summer long and have noticed a difference in moisture content. My hair is more softer and isn't as dry like it was when I washed my hair with shampoo.