Kohl is a black substance used by the women of the Arabian Peninsula as eyeliner and eyeshadow. It is originally taken from a black stone known as Al Athmed which is brought from Saudi Arabia. This stone is heated until it disintegrates and then it is processed in water and Arabian coffee or sometimes henna leaves and it is left for forty days to process. Finally, it is ground into a fine powder and it is ready to be used as an eyeliner for the eyes.

These days, some eye cosmetics may be labeled with the word kohl, but the word only indicates the shade. When applied to the eye, it gives the same effect of the original Arabian kohl, which is a larger & brighter look.
What's funny about the original Arabian kohl is that it's actualy water-proof but not spit-proof!