The mineral content of plants, animals, and humans is inorganic and is that material which remains after either thermal (fire or high temperature) or chemical (nitric or perchloric acid) oxidation. Essential minerals are part of major organ systems, proteins, enzymes, and hormones, and regulate metabolism. In animals and humans, minerals constitute about 4% of our adult body weight. All minerals in the diet are not equally absorbed, nor are all different compounds and complexes of the same mineral absorbed with the same degree of efficiency. Such differences in absorption, along with factors such as age, sex, genetic variables, general health, nutritional status, and diet, affect mineral absorption and bioavailability. The chapter presents the minerals in decreasing order of abundance in the human body. For each mineral an overview of its absorption, modes of excretion, and metabolism are also presented.