Addiction is a condition in which an individual cannot function without a certain substance or activity. In medical terms, addiction is a chronic and recurring disease that lasts for a long time. Drug addiction, on the other hand, is characterized by constant and long-term use of a substance. Psychic addiction, on the other hand, is the need to use a substance due to prolonged experiential and psychological effects, such as euphoria, which is an increased feeling of pleasure. Physical dependence is a condition in which the lack of a substance leads to disturbances in the proper functioning of the organism, and unpleasant symptoms of an abstinence crisis appear. This condition is usually accompanied by the need to increase the dose in order to achieve the effect that the substance initially caused with a smaller amount. A drug is any substance used to affect the central nervous system of the brain, and can be categorized as legal (such as alcohol and tobacco products) or illegal, such as street drugs. Currently, the focus on addiction has expanded to include not only drug addiction, but also "new addictions." These addictions are not substance-based, but are related to certain types of behavior, such as addiction to modern technologies such as social media, the Internet, and video games, as well as gambling addiction.