This active is full of strong chemicals (1,8-cineole, alpha-piene, alpha-terpinene, terpinen-4-ol and many many more) with the ability to kill many types of bacteria, fungi and even insects such as head lice.
It is commonly used to control acne as it kills Propionibacterium acnes bacteria. The Tea Tree (teatree) Oil sold by Skin Actives is pure, and must NOT be used straight on the skin.