Testosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.
Testosterone is the male hormone responsible for reparing and building muscler tissue,deepening of the voice,growth of body hair,aggressivesness,etc.
Taking testosterone in steroid form will cause rapid muscle growth in the user along with some probable side affects:acne on face or body,increased body hair,bad breath,and the list goes on