Addiction is defined as a psychological and/or physiological dependency on a particular substance or event. Common addictions include illegal drugs, alcohol, tobacco, and gambling.
If the addiction is purely governed by a psychological drive, then it is known as a psychological addiction or psychological dependency.
If the patient’s bodily mechanisms require the drug (i.e. if s/he feels physically ill if the drug is withdrawn) this is known as physiological addiction.
Any time a person continues to exhibit harmful or obsessive behavior, we can say that they are addicted. There are many, many types of addictions, from gambling, to sex, to drugs and alcohol.