Gap refers to the phenomenon that the stock price jumps up and down sharply after being affected by bullish or bearish. When the stock price rises under the influence of bulls, the opening price or lowest price of the exchange on that day is higher than the closing price of the previous day by more than two reporting units, which is called "gap". When the stock price falls, the opening price or the highest price of the day is lower than the closing price of the previous day by more than two reporting units, which is called "jumping down". Or in a day's trading, it rises or falls by more than one reporting unit. Gaps usually appear before the beginning or end of a sharp change in stock prices.