Slippage means the dissimilarity between the expected price of a position as well as the price where the position is made. Slippage frequently happens while in periods of biggest movements, whenever market trades are utilized, also whenever large positions are made when there might not be sufficient interest at the preferred price level to keep up the estimated price of position. Also, sometimes only we might see Slippage, especially when any important financial or economic news released during news sharp rise/fall in the market price, and sometimes you open the position at the different price but due to sharp movement your order filled at the different price.
