Testosterone is a hormone that is produced primarily in the testicles for men and the ovaries and adrenal glands for women. This hormone is essential to the development of male growth and masculine characteristics. For women, testosterone comes in much smaller amounts. Testosterone production increases about 30 times more during adolescence and early adulthood. After early adulthood, it’s natural for levels to drop slightly each year. Your body may see a one percent decline after you’re 30 years old.
Testosterone plays a key role in your:
The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine .