Depression is a common mental illness that belongs to the category of affective disorders. Depression is mainly characterized by three major symptoms, namely, depressed mood, slowed thinking and depressed will, which can be manifested as low mood or depression, reduced pleasantness, reduced interest, reduced energy, easy to feel fatigue, reduced activities, poor self-confidence, low self-esteem, pessimism, etc. In life, it can be manifested as “reduced ability”, such as learning or The patient may experience a “reduced ability” in life, such as a decrease in learning or work efficiency. Other patients have physical symptoms, such as insomnia, loss of appetite, headache or dizziness, and back pain. The symptoms are often overlooked because they are similar to those of common medical conditions. Patients with severe disease may become pessimistic and anxious, desperate or even suicidal attempts and behaviors. Depression can be classified as primary or secondary according to the cause. Primary depression refers to depressive symptoms that are not obviously associated with other diseases, while secondary depression refers to depressive syndromes triggered by other diseases. Some endocrine diseases, metabolic diseases, vascular diseases, immune abnormalities, psychiatric diseases, neurodegenerative diseases, trauma, inflammation, infection, poisoning, and drug abuse can cause secondary depression. Although the symptoms of depression are diverse, affecting all aspects of the depressed person’s life and ultimately disrupting their normal life, all depressions are treatable. Without treatment, major depressive disorder can be dangerous. Suicidal tendencies are a common symptom of this disorder. Although people who are deeply depressed are rarely capable of committing suicidal acts, they do so when they begin to get better. In the United States, untreated depression is the most common cause of suicide.