According to the dictionary definition, dependence refers to a submissive, obedient state characterized by the loss of personal freedoms.

Many people consider that their goal in life is to have a pleasant, easy and active life, a good social status that satisfies them and those around them, and to control their life and psychological mental state.
A mixture of these goals can cause a dependence. A general rule says that if a behaviour is followed by a pleasant outcome, this behaviour will be repeated in the near future. However, this behaviour is reinforced rather than dropped, if its expected outcome does not follows the behaviour each time.

From a psychological point of view,
dependence refers to an excessive, abnormal and harmful behavior.

It might sound incredible, but almost all human activities - such as working, feeding, sex, collecting valuable materials, taking pills, drinking alcohol , and taking drugs can turn into a dependence.

personal dignity injuries.

Once a person loses his/her freedom, their personality starts slowly and insidiously to change. A self-dilusional reality created by the addict from lies and twisted explanation to protect him/her from losing the his/her self-esteem and other people's respect, stops the addict from becoming aware of these changes.

Many people do not like to be called substance dependents, because this term is perceived throught its negative connotation. Liberty, self-determination, self-control, social functions fulfillment, and health are few of the most valuable society traits. As long as people are dedicated to their personal pleasures and pasions without losing their health, social status, or work ability, they will not be called substance dependents or maniacs.
These terms (substance dependents and maniacs) are only used when these values (liberty, self-determination, self-control, social functions fulfillment, and health) are impaired, when the person's life perspective and interests narrow, and when the addictive behaviour becomes dominant (without being followed by its initial satisfaction). Finally, the alcoholic discovers that drinking offers no satisfaction. A similar situation is faced by an workoholic (a person who is work addicted) who continues to work excessively even when he/she has lost the interest on the work results and success. The dependence's inner dymanimcs leads to a progressive incapacity to perceive pleasure and a general loss of life appetite.

There are two types of dependences: physical dependence and psychological dependence.

The physical dependence is caused by the constant, frequent and abusive consumption of harmful substances. The body adjusts to these substances causing an increased tolerance. In this state, the addict's body needs the substance to function normally.
The physical dependence occurs when the addict stops using the substance, and is characterized by a so called withdrawl syndrome (unpleasant physical symptoms). The body will function normally only when the person start re-using the substance.

We can talk about a psychological dependence when the addict displays an inner desire and then an obsessive need to consume the harmful substance in order to achieve pleasurable outcome or to avoid the discomfort.
A psychological dependent uses that substance to obtain a comfortable psychological state, and to cope with stressful situation and low spirits. When the addict cannot consume the substance, he/she experiences uncomfortable feelings (even fear).

It is possible for the psychoholical and physical dependence to develop independently.

Each substance dependent displays a typical, unhealthy and disfunctional attitude long before the actual onset of the dependence. When the dependence develops, decisive for it's onset is the person's need to use the substance in order to achieve certain outcomes, and not the actual substance use.