As far as I know, there are two broad types of addiction... physical addiction and psychological addiction. In terms of addiction to substances, people that become physically addicted to a substance will experience physical withdrawl symptoms if that substance is taken away. Psychological addiction is based on repeatedly trying to fix a psychological issue with a substance.
People are much more likely to become psychologically addicted to alcohol than physically addicted. Alcohol provides an escape mechanism for social issues, it is that quality that makes it addictive, it doesn't need to have the same level of physical addictiveness of other drugs in order to be addictive.
People are much more likely to become psychologically addicted to alcohol than physically addicted. Alcohol provides an escape mechanism for social issues, it is that quality that makes it addictive, it doesn't need to have the same level of physical addictiveness of other drugs in order to be addictive.