Discounting is an act of converting forward currency into cash. For example, if you have an acceptance bill or time deposit certificate due in three months, and you need to use cash now, you can change it into cash. However, if the person who accepts it loses interest for three months, then deduct the interest loss from the cash given to you. Then, the negative deposit interest you pay is the negative interest you need to bear when discounting (equivalent to "loan interest", but there is no "loan interest" in interpersonal communication.