Generally, it is not called preface, but preface. It is an article placed before the body of the book. The author's own writing is called "preface", which mostly explains its content, writing reason, process, theme and characteristics. The preface written by others is called "preface", which introduces and comments on the ideological content and artistic characteristics of the book.
In ancient times, there was another kind of preface, that is, farewell words, which was called "preface of giving words" Most of the content is words that praise, emphasize or encourage relatives and friends. For example, Song Lian's "Preface to seeing Ma Sheng off to Yang" is the preface written by the author to the younger generation in his hometown. There is also a preface written in front of a poem, called "preface to poetry", which is more about telling the content of the story or the source of the poem. For example, Peacock Flying Southeast by Han Yuefu, Pipa Trip by Bai Juyi and Yangzhou Slow by Jiang Kui are all in order. The preface is written in a simple way, just explaining the relevant time, place, people and so on. Usually only a few dozen words are enough.