The common name for a cosmetic product used to darken the eyelashes is mascara.
Mascara is applied with a brush or wand to darken, thicken, lengthen, curl, or define the eyelashes. Modern formulas are commonly liquid, though powder and cream forms have also existed. Most contain pigments, oils, waxes, and preservatives; black and brown shades often use iron-oxide pigments.
The idea is ancient. Egyptians used kohl as early as about 4000 BC to darken the eyelashes, eyelids, and eyebrows. The modern product developed in the 19th century, when Eugène Rimmel made a petroleum-jelly-based cosmetic. In the United States, Thomas Lyle Williams created a similar product for his sister Mabel in 1915 and later built the Maybelline company around it.
Mascara is sometimes confused with eyeliner or eyeshadow. Eyeliner defines the skin around the eye, while eyeshadow colors the eyelids. Mascara specifically coats the lashes, although some formulas may also be used on eyebrows.