Reference books are different from ordinary books. 1, for the purpose of writing, is exploratory. Reference books are generally not for people to read from beginning to end, sentence by sentence and word by word, but for people to provide all kinds of information or clues, consult materials and solve difficult problems; 2. From the content materials, the reference books are average. It draws on extensive knowledge, draws lessons from extensive reference materials, and mostly removes the false from the true or makes incisive exposition on the collected materials, so the content is more extensive and summarized; Judging from the arrangement of materials, reference books are easy to find. It is arranged in a variety of ways, either by radicals, strokes or shapes, or by numbers, or by phonology, or in reverse order, or by classification and theme order, or by chronological order, or by region, with the aim of finding it at once and facilitating the search.

It is a kind of book that widely collects a certain range of knowledge materials and arranges them according to a certain method to solve difficult problems or provide information clues.