Squalane is a real goodie with great skin hydrating and emollient properties.
It occurs naturally in certain fish and plant oils, and in the sebum (the oily stuff our skin produces) of the human skin. The latter makes it an important skin-identical ingredient and a NMF (natural moisturizing factor).
It helps to protect the skin barrier and even demonstrates some antioxidant properties. It does not clog pores and leaves a non-greasy, non-heavy feeling on the skin.
Squalane is the hydrogenated form of squalene, a lighter, more stable and less oxidative version of it. That’s why, it shows up more often in the ingredient lists.
You can read all about squalene here.