The preface of the paper is also called introduction, which is a short paragraph in front of the text. The preface is the preface of the paper, which aims to explain the ins and outs of this study to readers, arouse readers' interest in this paper, and play a role in outlining and guiding reading interest in this paper. Before writing the preface, we must first clarify several basic questions: What do you want to explain through this article? What are the new discoveries and whether they have academic value? After reading the preface, the general reader can clearly know why the author chose this topic for research. Therefore, before writing the preface, we should know as much as possible about the relevant contents, collect the main data of predecessors and others' work, and explain the rationality of this study. Introduction, as the beginning of an academic paper, briefly introduces the writing background and purpose of the paper, the origin and realistic requirements of the research, as well as the preliminary work and research survey in related fields, explains the relationship between this research and the preliminary work, the current research hotspots, existing problems and the author's work significance, and leads to the theme of this paper to guide readers. The introduction can also point out the theoretical basis, experimental basis and research methods of this paper, and briefly explain its research content; A few words foreshadow the results, significance and prospect of this study, but there is no need to discuss it. The preface should include: Why do you want to do this research? What is the theoretical or practical basis for setting the topic? Want to innovate? What is the theoretical and/or practical significance? First of all, it is necessary to introduce the historical background and theoretical basis of this topic, the research progress and achievements of predecessors or others on this topic, and whether there are different academic viewpoints in academic circles. Tell the reader clearly why you want to do this research, and the sentences should be concise and straight to the point. If the research project has never been carried out by others, then the innovation is obvious, and the innovation of the research should be explained. But in most cases, research projects have been carried out by predecessors. At this time, it is necessary to explain the differences and essential differences between this research and that research, rather than simply repeating the work of predecessors. The content and format of the introduction (1) explain the theme, scope and purpose of the paper. (2) Explain the cause, background and brief historical review of related fields of this study (what have predecessors done? Which ones have not been solved? How's it going so far? )。 (3) Expected results or the significance of this study. (4) The introduction is generally not segmented, and its length depends on the content of the paper. The introduction of papers involving basic research is long, and the clinical case analysis should be short. The introduction of most foreign papers is relatively long, generally around 1000 words, which may be related to the strict limitation of words in foreign academic journals. (Source: Hans Publishing House, welcome to contribute)