Couplets are called "couplets", commonly known as pairs. Concise and profound, neat and balanced, word for word, is a unique art form of Chinese language. It can be said that couplet art is a cultural treasure of the Chinese nation. The types of couplets can be divided into Spring Festival couplets, wedding couplets, birthday couplets, elegiac couplets, decorative couplets, industry couplets, communication couplets and miscellaneous couplets (including humorous couplets ...). The length of couplets varies, only one or two words are short; It can be hundreds of words long. There are various forms of couplets, such as pairs, pairs, flowing pairs, couplets, set sentence pairs and so on. But no matter what kind of couplets are used, they must have the following characteristics: First, the number of words should be equal and the sentence breaks should be consistent. In addition to deliberately leaving a place for a word to achieve a certain effect, the number of words in the upper and lower couplets must be the same, neither more nor less. Second, we should be straightforward and harmonious. The traditional habit is to "pucker up and fall flat", that is, the end of the last sentence of the first couplet is puckered up and the end of the last sentence of the second couplet is flat. Third, the part of speech is relative and the position is the same. It is generally called "virtual to virtual, real to real", which means that nouns to nouns, verbs to verbs, adjectives to adjectives, quantifiers to quantifiers, adverbs to adverbs and related words must be in the same position. Fourth, the content should be related and run through from top to bottom. The meaning of up and down links must be interrelated, but they cannot be repeated. In addition, the traditional practice of hanging couplets must be written straight and pasted vertically, from right to left and from top to bottom, and cannot be reversed.

Horizontal criticism (or horizontal banners, rungs, banners, horizontal curtains, etc. ) is an important part of couplets. Horizontal comments, like the title of an article, can mark the theme of a couplet, which is the finishing touch and icing on the cake. Generally speaking, horizontal criticism plays a role in summarizing, revealing, supplementing and explaining couplets. From the scope of use, the most commonly used and original form of couplets is to stick them between couplets (so it is also commonly known as couplets). The upper and lower couplets, together with the horizontal comments on the lintel, are the "doors". Symmetry is the most obvious form of couplets, and the beauty of China's architecture lies in the traditional symmetrical form. Architecture and the structure of couplets set each other off, which is another reason why couplets are criticized. However, it does not mean that all couplets have horizontal comments. For example, some door plaques can be cross-commented, and cross-comments can be omitted for couplets and elegiac couplets (not suitable for hanging between couplets).