Oils

Our scalps naturally produce a waxy oil called sebum. It's there to protect the hair & scalp by locking in moisture and acting as an antimicrobial & antioxidant. But the structure of curly hair, particularly tighter curls and coils, makes it hard for sebum to travel down the hair strand, leading to dry, brittle, dull, tangle-prone hair. 

Oils are used to seal in water based products, keeping the hair moisturised, shiny and smooth.