Addiction is a condition in which a person engages in use of a substance or in a behavior for which the rewarding effects provide a compelling incentive to repeatedly pursue the behavior despite detrimental consequences. Addiction may involve the use of substances such as alcohol, inhalants, opioids, cocaine, nicotine, and others, or behaviors such as gambling; there is scientific evidence that the addictive substances and behaviors share a key neurobiological feature—they intensely activate brain pathways of reward and reinforcement, many of which involve the neurotransmitter dopamine.

There is no one cause of addiction. Although genetic or other biological factors may contribute to vulnerability to the condition, many social, psychological, and environmental factors have a powerful influence on substance use. There is no one personality type associated with addiction, either. The lack of ability to tolerate distress or other strong feelings is linked to addiction.

The road to recovery is seldom straight: Relapse, or recurrence of substance use, is common—but definitely not the end of the road. For those who achieve remission of the disorder for five years, scientists report, the likelihood of relapse is no greater than that among the general population.

https://www.psychologytoday.com/us/basics/addiction