K-line chart, also known as candle chart, daily line, yin-yang line, bar line, etc. K-line, commonly known as "K-line", originated from the rice market transactions in the Tokugawa shogunate era (1603 ~ 1867) in Japan in the 8th century, and was used to calculate the daily rise and fall of rice prices. Because of its unique drawing method, it is introduced into the analysis of stock market price trend. After more than 300 years of development, it has been widely used in stock, futures, foreign exchange, options and other securities markets. There are three kinds of commonly used K-line diagrams: one line connects the K-line with a single target price; Candle chart K-line chart; K-line chart of Europe and America.