It is more difficult to reach the post-doctoral level. Only a few people can do it. A postdoctoral fellow refers to a person who engages in academic research in an institution of higher learning or research after obtaining a doctorate, usually working in a postdoctoral mobile station or postdoctoral research center. It should be noted that postdoctoral fellows are not degrees, but work experience. In China, getting a doctorate is a necessary condition for becoming a postdoctoral fellow.