Our hair is dead once it breaks through the surface of the scalp, as Jasmine Merinsky, a Toronto-based hairstylist, explained to HuffPost. And if it weren’t for our sebaceous glands, which secrete natural oils, that hair would be dry and brittle.

“Similar to skin, we need oil to have healthy, strong hair,” Merinsky said. “Oil lubricates the outer cuticle and strengthens the inner core by providing moisture to help keep the bonds strong.”

Everyone’s scalp and hair are different and some people are just oilier than others, she added.

That’s where hair oils come in. The store-bought product is meant to replicate and supplement the natural oils that our bodies already make. Plus, Merinsky said, hair oils smell nice and provide you with control over the amount and application.

Bobby Eliot, a Los Angeles-based celebrity hairstylist with Starworks Artists, told HuffPost that hair oils can be used both as a nourishing treatment and as a styling tool to help smooth the hair.