The term addiction (addiction) is widely used in everyday life. Addictive behavior generally has the following characteristics: the addict has a strong desire to do a certain behavior, but the result of the behavior is harmful to others and to oneself. If the addiction is not controlled, the tension and anxiety gradually increase, and once the behavior is completed, the tension and anxiety are quickly and temporarily relieved. However, after a period of time, such as a few hours, days or weeks, the desire to perform the behavior reappears, and external and internal environmental stimuli can often induce this desire. Eventually the addict hopes to control the behavior, but repeatedly fails. That is, the compulsivity of the behavior, i.e., the strong motivation to engage in a behavior regardless of the consequences, and the persistence of the behavior, i.e., the loss of control of the behavior, lead to the persistence of the addictive behavior. Addictive behaviors can be broadly classified as: chemical addiction, such as heroin, ecstasy, marijuana, ketamine, marijuana, etc.; non-chemical addiction, such as computer network addiction, pathological gambling, etc. From a medical perspective, addiction, also known as dependence, is defined as a group of cognitive, behavioral and physiological symptoms that indicate that an individual continues to use an addictive substance despite understanding that it causes significant problems, and that self-medication results in increased tolerance, withdrawal symptoms and compulsive drug compulsive drug seeking behavior). (Note: Compulsive drug seeking behavior is the impulsive use of drugs by the user, regardless of all consequences, and is a manifestation of loss of control of the self, not necessarily a problem of weak will and moral turpitude as often understood). Substances, psychoactive substances, and drugs are a class of chemical substances that can affect the human mind, emotions, behavior, alter the state of consciousness, and have a dependence-causing effect, and are used by people for the purpose of obtaining or maintaining certain specific psychological and physiological states. Psychoactive substances are also known as substances or addictive substances (substance), drugs (drug). We often refer to drugs as a sociological concept, which refers to chemical substances that are highly addictive and prohibited in society, and drugs in our country mainly refer to opioids, cocaine, marijuana, stimulants and other drugs. There are many substances that can produce dependence, and they can be divided into the following categories according to their pharmacological properties: 1. CNS depressants: they can inhibit the central nervous system, such as barbiturates, tranquilizers, alcohol, etc. 2, central nervous system stimulants: can excite the central nervous system, such as caffeine, amphetamines, cocaine. 3, marijuana: marijuana is the world’s oldest and most famous hallucinogen, moderate inhalation or consumption, can make people euphoric, increase the dose can make people enter the dream, into a deep and refreshing sleep, the main component of Δ9 tetrahydrocannabinol. 4, hallucinogens: can change the state of consciousness or perceptual feelings, such as lysergic acid diethylamide (LSD), cactus toxin (mescaline), etc. 5, opioids: including natural, synthetic or semi-synthetic opioids, such as heroin, morphine, opium, methadone, etc. 6, volatile solvents: such as acetone, phencyclidine (PCP), etc. 7, tobacco (nicotine). In the above addictive substances, some of them are available in stores, such as cigarettes, alcohol, they are mainly used in social situations, also known as social addictive substances. Some can be bought in hospitals or pharmacies, also known as prescription drugs. There are also drugs that are forbidden to be used in any setting, such as heroin and marijuana, which are called illegal addictive substances. Addictive behaviors are very harmful, so if you have any related problems, please consult and treat them in a professional institution as soon as possible!