History is an objective fact and there is only one truth. However, the knowledge of recording and studying history often changes, develops and perfects with people's subjective consciousness, and even distorts and fabricates it. There are many different interpretations of the meaning and essence of history, some of which are listed below. Croce said: "All history is contemporary history." Collingwood said, "All history is the history of ideas." Liang Qichao: "Who is a historian? Describing the continuous activities of human society, checking its total achievements and finding its causal relationship are also a reference for the activities of modern ordinary people. " Encyclopedia Britannica (version 1880): "The word history has two completely different meanings in use: one refers to the events and actions that constitute the human past; The second refers to the description of this past and its research model. The former is what actually happened, and the latter is the study and description of what happened. " Encyclopedia of the Soviet Union: "1, the development process of any event in nature and society. The history of the universe, the history of the earth, the history of various disciplines-the history of physics, the history of mathematics, the history of law and so on. Can be included in this meaning. 2. A discipline that studies the concrete and diverse past of human society, with the purpose of explaining the concrete present and future prospects of human society. " History does not belong to humanities or social sciences, but builds a bridge between them and combines the research methods of the two fields. Generally speaking, historians try to answer questions related to history by studying various languages, but they are not limited to this. The original materials of historical knowledge can be divided into three types: written records, oral records and preserved historical sites. Usually, historians will make a comprehensive study of them, and written records are often emphasized because they generally record the time of development. This emphasis has led to a new field, prehistory, also known as prehistory, which studies the period without written records. Because people appear at different times around the world, the main difference between prehistory and history is determined according to specific topics. In order to facilitate research, scholars divide human beings into different stages according to their past scope. There are many ways to divide the past, including by age, by cultural customs and by different themes. These three categories often overlap, such as "The Evolution of Labor Movement in Argentina, 1930- 1945". Although historical research tends to focus on some special places, times and themes, historians also care about other ordinary contents. For others, history has become a very common word, that is, the study of everything in the past, and now even the so-called generalized history has arisen. In the past, learning history was all about application or theory, but now there is another one: curiosity about human past.