The so-called K-chart of foreign exchange is to graphically represent the daily (weekly and monthly) opening price, closing price, highest price and lowest price. Foreign exchange K-line, also known as Yin-Yang line, bar line, red-black line or candle line, originated from rice market transactions in Japan and has become an important method in technical analysis.

In practical application, there are still many investors who like to use histogram. The structure of bar chart is simpler than that of foreign exchange K-line chart, which is mainly drawn by Europeans and Americans. The straight line part of the bar chart represents the fluctuation range between the highest price and the lowest price of the market on the day (or week). The horizontal line on the left represents the opening price and the horizontal line on the right represents the closing price. Traditionally, the opening price on the left is often omitted, and only the highest price, the lowest price and the closing price are indicated.