House of Mind

• Experimental use: Usually represents a benign category that marks the initiation of use. This kind of use is limited to few exposures, no development of a regular pattern of use, and relatively no substance-related harm or consequences. Experimental use is usually sparked by a curiosity to experience and usually takes places in social situations. Ex. Being curious about cigarettes and having a couple of puffs. 
• Occasional use: Another relatively benign category. Social or recreational substance use falls into this category. Substance use typically infrequent and irregular and in modest consumption. This one is tricky because it is common for a patient to report irregular use even when a pattern is starting to develop. Ex. Drinking limited to social situations.
• Regular use: Use becomes more frequent and patterned as people shift from occasional to regular use. Some people move so quickly that they hardly notice when the transition into regular use occurs. Once the person becomes habituated, a regular pattern emerges. However, regularity of use may or may not be an indicator that loss of control has happened. The reinforcing properties of a drug become seductive once a person reliably achieves desirable changes in mood and feelings after administering the drug. Ex. Drinking/smoking almost every day. 
• Circumstantial use: This category includes various patterns in which the substance is used to produce specific types of effects deemed desirable to enhance an experience or to better cope with certain situations. Ex. Taking Adderall for a late night cram session before a big test. 
• Binge: An episodic pattern in which large quantities of alcohol/drugs are consumed intensively in a marathon-like fashion during a single episode of use. Binges maybe punctuated with long period of abstinence or little/no craving.  Ex. Blowing through many lines of cocaine through one night. 
• Abuse: Individual manifests significant substance-related problems repeatedly in important areas of functioning (health, legal, social). Many people who show signs of abuse do not progress to substance dependence. Ex. Using drugs even when you’re on probation, despite being advised of the consequences of pissing a positive. 
• Dependence: The most troubling category as evidenced with a preoccupation with obtaining and using the drug, an inability to control consumption in a dependable manner, impairment in psychosocial functioning, and continued use despite adverse consequences. Ex. A mom that had her kids taken away because of her drug use wants them back, but is unable to stop using.

Taken from Treating Alcohol and Drug Problems in Psychotherapy Practice: Doing What Works by Arnold M. Washton and J.E. Zweben. Part of my psychology of addiction reads.