dude dont post stupid questions in a forum expecting everybody to explain it to you when you can get the basic knowledge by your own research, im sure wiki would give u a basic enough answer

Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testicles 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. You must not be old enough to produce testosterone..

Gotta be a kid...how old are you?

you cant google?