The difference between the high and low price of a products such as stocks, commodities, foreign currencies etc are bought and sold in market on given trading session, week, month, year, etc.
Whatever task that you undertake, do it with all your heart and soul. Always be courteous, never be discouraged. Beware of him who promises something for nothing. Do not blame anybody for your mistakes and failures. Do not look for approval except in the consciousness of doing your best.
To sell a previously purchased futures or options contract or to buy back a previously sold futures or options position. Also referred to as Offset or Square off or Close out