What is drug abuse?

Drug Use:
Anytime a person consumes a psychoactive substance for any reason (such as recreational, experimental, etc,) they are involved in drug use. It becomes harmful when the user misuses it or depends on it. The opposite of Drug-use would be “Drug-Free”. 
 
Drug Misuse:
Misuse is taking drugs that threaten the physical, mental or social state of the person.

Drug Abuse:
This is simply a pattern of using drugs that leads to impairment or distress after a while. Such impairment may include failure to do work, go to school, drive, or even interact with people socially. 

 
Abuse is often followed by Dependence. This is when the individual now needs more of the drug to achieve the desired effect. At this stage, the individual is willing to sacrifice some good or normal personal values to acquire and consume the drug. They may steal, break a law, or do something not cool to get the drug.
 
Addiction:
Drug addiction by definition is a chronic, relapsing brain disease that is characterized by compulsive drug seeking and use, despite harmful consequences.
 
Addiction is right next to the Dependence stage. Some people use addiction and dependence interchangeably. Addiction is severe, marked by a change in behavior caused by the biochemical disruptions in the brain. Regardless of the harm that it can cause, an addict is unable to restrain themselves for more drugs.