There is a clear difference between depression and depression, having depressed mood is not necessarily depression, depression will definitely have depressed mood. Depressive mood is a normal negative emotion of people, mostly occurs when people experience bad things, people will experience such an emotion, such as feeling aggrieved, sad, angry, etc.. Depression is diagnosed if it lasts for more than two weeks and the symptoms meet the following points: first, the core symptoms, including depressed mood, lack of interest and low energy. Second, there are additional symptoms, including 1) low self-confidence and low self-esteem; 2) self-blame or self-guilt; 3) thoughts of death or suicide, or suicidal behavior; 4) slowed thinking, poor concentration, and memory loss; 5) slow reaction, inefficiency, or excessive focus on one thing; 6) sleep disorders; 7) sexual dysfunction; 8) changes in appetite and corresponding weight changes. Depression can be diagnosed if there are two of the above core symptoms and then two additional symptoms, plus depressive symptoms for more than two weeks.