The “Spot Price” of any precious metal is the price at which someone can expect to receive immediate sale of the commodity. The spot price is generally lower than what you can buy the metal for at that time as most merchants will add a premium “above spot”. This price often reflects what the future expected price of the metal is to be. The spot curve is the result of the calculations and takes into account the amount of time between the current price and the spot price.
Silver Chronicle » What Is Spot Price?