A moustache is facial hair grown on the outer surface of the upper lip. It may or may not be accompanied by a beard, hair around the entire face.
The moustache forms its own stage in the development of facial hair in adolescent males. Facial hair in males normally appears in a specific order during puberty:
The first facial hair to appear tends to grow at the corners of the upper lip (age 11-15),
It then spreads to form a moustache over the entire upper lip (age 16-17),
This is followed by the appearance of hair on the upper part of the cheeks, and the area under the lower lip (age 16-18),
It eventually spreads to the sides and lower border of the chin, and the rest of the lower face to form a full beard (age 17-21).
As with most human biological processes, this specific order may vary among some individuals depending on one's genetic heritage or environment.
Moustaches can be tended through shaving the hair of the chin and cheeks, preventing it from becoming a full beard. A variety of tools have been developed for the care of moustaches, including shaving razors, moustache wax, moustache nets, moustache brushes, moustache combs and moustache scissors.

en.wikipedia.org/wiki/Moustache