Simply put, melanin is pigment, but there are two types of melanins that give hair and skin its distinctive coloring. Let's start with pheomelanin, which lends reddish tones to the body.
While pheomelanin can be found in light- and dark-skinned people, females tend to have more of this type of pigment in their skin than men do. Hence, you'll often notice a slightly more pink or reddish quality to a woman's body. Also note that pheomelanin is more concentrated on the lips, nipples, and girly parts.
Even though we all have at least some pheomelanin in our hair, if you're a redhead, you're loaded with it, as it's what is responsible for imparting those fiery reddish tones to your locks. But don't forget about blondes, however, as pheomelanin, thanks to its yellowish tones within, works to determine the pigmentation of golden-haired beauties, too.