it is a lifelong known fact that nicotine is tobacco's drug ingredient. sorry, my 'net is dial-slow-up... if you google nicotine, there are some interesting articles about all the effects of nicotine. many good or pleasant, except CANCER related ones! if it is for homework, don't try to convince on the positives of smoking. a lot of other things (paper for starters) is in cigaret smoke.
BEST WISHES!