Final answer:
Coloration of skin is largely due to melanin, with contributions from carotene and hemoglobin, and is critical for UV protection. Melanin is produced by melanocytes and transferred to keratinocytes, affecting our skin's tone and our body's sun defense mechanism.
Step-by-step explanation:
The coloration of skin, whether normal or pathological, is primarily due to melanin, although other pigments like carotene and hemoglobin also have a role. Melanin is produced by melanocytes found in the stratum basale of the epidermis and transferred into keratinocytes via a melanosome.
This pigment is responsible for the vast variety of human skin tones and is critical for protection against UV radiation. Conditions such as albinism and vitiligo affect the production or distribution of melanin, leading to a lack of pigmentation in certain areas of the skin.