K-line refers to the daily, weekly and monthly opening price, closing price, highest price and lowest price of various currencies, which are graphically represented. A thin line at the top of K-line is called the upper shadow line, and a thick line in the middle is the entity.

K line is the positive line, and the intermediate entity is indicated by blank or red. At this time, the length of upper shadow line represents the difference between the highest price and closing price, the length of entity represents the difference between closing price and opening price, and the length of lower shadow line represents the difference between opening price and lowest price.

K-line chart is a kind of chart source in Tokugawa shogunate era in Japan. It was used by businessmen in Japanese rice market at that time to record the market and price fluctuation of rice market. Later, it was introduced into stock market, foreign exchange market and futures market because of its ingenious and unique drawing method. At present, this chart analysis method is particularly popular in China and even the whole Southeast Asia.