Testosterone is majorly produced in Leydig cells in males. Additionally, organs like gonads, adrenals, and placenta make it in small quantities. The levels of it in the body affect general cognition and memory. Basically, it is a male sex hormone. It is responsible for male sexuality. The hormone produces features like muscle mass, facial hair, and libido. Apart from that, testosterone also plays a significant effect on psychology and physiology. At 30, its count reduces gradually.