Smoking is terrible for the body. It causes cancer, damages nearly every organ in the body, messes with your brain, and it is addictive, so it'll be hard to quit. By then, your body will be very damaged. Other parts it damages are the:
Heart
Bones
Immune system
Lungs
Mouth
Reproduction system (if you're female)
Skin
All in all, you should not smoke if you want to live a happy, healthy life.