1) Tobacco affects the brain
Too much intake of tobacco creates special receptors in brain to deal with extra tobacco in taken by body. Those receptors keep demanding more tobacco making it utterly hard for the smoker to quit smoking.
2) Change in facial features
Smoking affects overall body along with the face. The face is our mirror of age. Smoking adds numbers to your face by making wrinkles all over the face and dark circles around the eye. Smoking affects the skin gravely. The skin loses its elasticity and glaze.
This is the most important part affected by smoking which is a well known fact. Smoking is the sole reason of lung cancer. Over the years, the net amount of taken nicotine stores in lungs and affects proper functioning of lungs.