Testosterone is a hormone that is produced solely in males. Lack of its production can have severe consequences. Testosterone is responsible for giving all the characteristics present in a male who has achieved puberty. Testosterone causes the growth of hair over the body. Over time it also causes the male pattern baldness. It causes the enlargement of larynx and that results into deepening of voice. It causes thickening of the skin and activates the sebaceous glands present under the skin which can cause acne. Moreover, there is an increase in the muscular development as there is an increase in the formation of proteins. It also causes calcium retention and increase in the bone matrix. There is also an increase in the basal metabolism rate overall. This hormone is given exogenously if produced in a lesser amount because it is an essential hormone.