The cells that produce melanin are called melanocytes and are present in the bottom layer of the skin's epidermis, the middle layer of the eye, the inner ear, meninges, bones, and heart. The color of the skin is regulated with the help of the pigment melanin. The pigment granules of melanocytes are transferred to adjacent epidermal cells through dendrites. The impact factor of the journal provides a quantitative assessment tool for grading, evaluating, sorting, and comparing journals of a similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.