Addiction is defined as the dependence of a person on a substance or an activity which generates pleasure, which the person can no longer go without despite his/her own will. Numerous addictions exist with more or less serious consequences depending on the case, from the everyday caffeine addiction to the dangerous addictions to drugs such as heroine. The latter can cause physical and mental problems, or even the death of the addict. Addiction can be psychological and/or physical, with the body suffering from a lack of the substance after withdrawal. There are also addictions to gaming (gambling as in a casino) and to exercise.