Both crack and cigarettes are chemically addictive. I don't know about crack but I know that nicotine actually makes your brain produce more receptors to "catch" the nicotine and process it. When you start smoking (tobacco) your body can't deal with all the nicotine so it creates many more receptors. Once you have all these new rectors, if you quit smoking then they have nothing to do. They tell your brain that you NEEEEEEEEEEEEEEEEEED more nicotine so you go buy another pack.weed isnt addicting like crack or even cigarettes its like sex your not addicted to it but you still really want it
Not sure how crack works but I would imagine it is simpler.