Although widely used, the term addiction is disputed as it has a range of definitions and uses. Some people who describe their experiences and behaviour as an addiction or who are described as having an addiction can have very personal and specific definitions of addiction.

Even where definitions are agreed, there are different views on the significance of addiction.

As a medical term, drug addiction is described as a chronic, relapsing disease characterised by compulsive drug seeking and use, despite serious adverse consequences, and by long-lasting changes in the brain. All aspects of this definition are open to challenge; as is the notion that addiction can always and usefully be regarded as a disease. (see disease model)

The notion that problem substance use is hereditary is sometimes proposed. There is much evidence to counter this and suggest that problem substance use is closely related to poverty and childhood trauma (see poverty, see adverse childhood experiences) trauma in adulthood; (see trauma) and social situation (see drug, set and setting; see Vietnam veteran studies; see Rat Park)