Red is the bottom line of riverside birds, and silkworm is a worm on earth. The antithesis of couplets is neat and even, with one word and one sound, which is a unique art form of Chinese language. Couplets are the treasures of China traditional culture. It is a dual literature, which originated in Fu Tao. It is a antithetical sentence written on paper, cloth or engraved on bamboo, wood and columns.

Couplets, also known as couplets, couplets and door equivalents, are an applied style with a long history and appeal to both refined and popular tastes, and are unique literary treasures of China people. It requires equal words, conciseness, neatness and balance, and it is a unique form of literary expression.

Couplets are composed of three parts: horizontal approval, upper couplet and lower couplet, which are widely used in Chinese New Year, famous mountains and rivers, home, weddings, opening and other occasions. Generally speaking, the knowledge and rules of couplets are mainly aimed at upper and lower couplets. The number of words online equals the number of words offline. The number of words in each clause of the long couplet is equal. There is a special case that the number of words in the upper and lower couplets is intentionally different.