Anxiety is a common emotional state, but it is also complex and mysterious. In his book “Introduction to Psychoanalysis”, Freud wrote: “One thing is certain, the problem of anxiety is a pivot linking various important psychological problems, and unraveling its mystery will surely bring light to all aspects of our spiritual life”. What people usually call anxiety is anxiety caused by real causes, which is normal anxiety, or called reality anxiety. Have you ever experienced anxiety? Some people may say that this is an obvious question, because people living in the real world always have to be anxious, because when one faces survival and development, one is bound to encounter various problems including life, old age, sickness and death, as well as various difficulties and challenges, and even dangers or calamities, which can cause tension, anxiety, worry, apprehension, fear, and even fear or panic. For example, going to school today to take an exam that you only started studying for yesterday, going on a date with someone you are in love with in the evening, and having a promotion exam next week that is important to your career, are things that might make you nervous just thinking about them. In theory, normal anxiety can be self-controlled by the individual, but this is not the case. Normal anxiety is also characterized by recurrence, and it will only ease or disappear when the cause of the anxiety is removed or disappears, or after readjusting to the environment. There is no consensus definition of anxiety in the medical community. Different disciplines have different definitions of anxiety and different schools of thought have different interpretations of it, for example, the behavioral school differs from the psychoanalytic school in its interpretation of anxiety, while this book discusses anxiety as defined by psychiatry, which is what is referred to as anxiety in clinical practice. In the medical literature before the 1980s, clinical anxiety was mostly defined as anxiety without a cause, as illustrated by the interpretation of anxiety in the Dictionary of Psychiatry (6th edition). This entry uses Piotrowski’s definition: anxiety is “an unpleasant emotion of a particular nature that is different from other emotions. At the same time, it also defines the mental activity and somatic state of anxiety as described by others: 1. In the mental aspect, anxiety is a special attitude of inner consciousness and a special state of feeling: (1) a sense of imminent and almost inevitable danger; (2) a painful physical and mental inability to do anything for oneself; (3) a nervousness and alertness as if in the face of (4) anxiously preoccupied with one’s own feelings, which prevents one from dealing effectively and profitably with reality; (5) trapped in unresolved doubts, including doubts about the nature of the danger, the likelihood of the danger actually occurring, the best objective way to reduce or remove the danger, and one’s subjective ability to use these methods effectively when the danger arises. 2. In terms of physical symptoms, anxiety can be accompanied by a variety of physical symptoms: mainly symptoms of increased sympathetic activity, such as increased heart activity, increased heart rate, increased or difficult breathing, pale or red face, sweating, increased muscle tone, tremor or paralysis, and abdominal discomfort. We can see from the description of Piotrowski’s definition that the medical definition of anxiety is anxiety without a cause (anxiety without a name), or free-floating anxiety derived from the Freudian view. The American Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV, 1994) defines anxiety as “apprehensive anticipation of impending danger or misfortune, accompanied by symptoms of poor mood or somatic tension.” In the Review of General Psychiatry, 5th edition, edited by Goldman, anxiety is defined as “a fear-like state of emotional distress (unpleasantness) in the absence of obvious risk factors”. The American Psychiatric Association (APA, 1994) and Barlow (2002) define anxiety as “a negative emotional state characterized by somatic symptoms of physiological stress and apprehension about the future”. These definitions are similar to Piotrowski’s definition of anxiety above. Many psychological disorders are characterized by excessive anxiety, but manifest themselves in different ways, such as fear and panic, which are closely related to anxiety. Fear is an immediate alert response to danger. Like anxiety, fear is a common emotional response, and moderate fear is beneficial to people. It activates a large number of autonomic nervous system responses (e.g., increased blood pressure, increased heart rate, etc.), and these somatic responses, along with subjective fear, give us the ability to flee or attack. This emergency response is often referred to as the flight or flight response. Currently, there is academic consensus that fear and anxiety are psychologically or physiologically distinct: anxiety is a future-oriented state of mind characterized by uneasiness because we cannot predict or change future events, whereas fear is an immediate emotional response to current danger characterized by a strong tendency to escape and often accompanied by acute autonomic arousal (Barlow, Brown & Craske, 1994). Craske, 1994). The word panic originates from ancient Greek mythology. In ancient Greek mythology, Pan was a nature god who lived in the countryside and was in charge of rivers, forests, and birds and animals. Pan was short, ugly, and had two goat legs. He often likes to rest in small caves or bushes by the roadside, and if disturbed by others, will let out a creepy scream, which is not a good thing for travelers or passers-by. Many Greeks in a hurry accidentally disturbed him, the result was this terrible sound scared to death. And this sudden, excessive reaction became known as panic (panic), and was named after this enraged god. In psychiatry, a panic attack (panic attack) refers to a sudden, highly fearful or very uncomfortable experience accompanied by physical symptoms such as palpitations, chest pain, shortness of breath, and/or fainting. Numerous studies have confirmed that the experience of panic reports many similarities to fear, including similar tendencies to avoidance behaviors and similar neurobiological processes.