Skin gets its colour from melanocytes. Melanocytes are cells which produce the brown colour, melanin. These cells are produced in the lower level of the epidermis. Everybody has the same number of melanin cells. What causes a difference in skin colour is the way that the cells are distributed in the skin and the quantity of the colouring substance - melanin that is produced.
For example, more melanin is produced by the cells when a person is exposed to sunlight. This is because melanin helps protect skin against the dangerous, burning, ultraviolet rays from the sun. In a 'Fairskinned' person there are only a few grains of melanin, but if that person lies in the sun, production in the melanin cells speeds up and the person begins to look darker in colour.
In a dark-skinned person, the melanocytes produce lots of melanin all the time. These people can stand a little more sunshine without getting burned, but not much. Sooner or later their blood vessels swell up and the skin becomes sore and burned.
