Addiction refers to the chronic or habitual use of any chemical substance to alter states of body or mind for other than medically warranted purposes. Common addictions are to tobacco products, drugs, alcohol, gambling, pornography.Traditional definitions of addiction, with their criteria of physical dependence and withdrawal have been modified with increased understanding and the introduction of new drugs, such as cocaine.
Addiction is more often now defined by the continuing, compulsive nature of the drug use despite physical and/or psychological harm to the user and society and includes both licit and illicit drugs, and the term “substance abuse” is now frequently used because of the broad range of substances (including alcohol and inhalants). Psychological dependence is the subjective feeling that the user needs the drug to maintain a feeling of well-being; physical dependence is characterized by tolerance and withdrawal symptoms when the user is abstinent. Tolerance occurs when it takes more and more of the substance to get the same amount of pleasure. Withdrawal occurs when you experience painful, and sometimes dangerous, symptoms when you go for any period without that substance. An addiction can be psychological, physical, or both.