What is Buy Stop order?

It is a pending order, which means to buy when the ask price gets equal to the specified value. Herewith, the current price level is lower than the value of the set order. Typically, the orders of this type are set in reliance on the assumption that the instrument price will overcome some level and continue to grow. It is impossible to set buy stop orders below the current ask price, you have to use buy limit orders for this.