What are the definitions of Substance Use, Abuse and Addiction?
One may try, experiment or start to Use drugs for many different reasons.

Recurrent use in the face of negative consequences - or signs of loss of control over use - indicate Substance Abuse. Sometimes the term Psychological Dependence is used to describe the habit of using a drug as emotional self treatment.

At the root of Substance Addiction is a lingering, recurrent and driving compulsion to use a substance that alters mental state or feeling. This compulsion is a pressured habit that has detached from any reasons why one started to use drugs in the first place. A compulsion has lost psychological meaning or rational sensibility.