You are having male pattern baldness also called androgenic alopecia. This occurs due to the influence of hormones on the hair roots.
Testosterone in the body gets converted into DHT and this Dht causes miniaturization of the hair from the front and the crown area of the scalp. Miniaturization means the hairs start getting thinner and ultimately they are lost. The back and the sides of the scalp are not affected as the dht receptors are not present in the hairs on those areas.
Since dht will act on the hairs all your life, male pattern baldness is progressive and will continue till you are completely bald. Hence, the treatment for male pattern baldness has to be done lifelong. Please visit me for treatment advice.