BOLL, short for Bollinger Bands, was created by Mr. John Bollinger. The crypto K-line graph uses statistical theory to calculate standard deviation and confidence interval for the purpose of determining the fluctuation range and future trend of a token’s price. Since it signifies the levels of highs and lows that price has reached, it is also called Bollinger Bands. Its bandwidth is not fixed, instead, it changes based on price. The band show the fluctuation limits of a token’s price, that is, the width of the belt region accordingly changes based on the price fluctuation. When the price experiences a greater decrease or increase, the bandwidth widens; conversely, when you see a narrower band, it shows a smaller change in price.