The difference in the cost of an asset or security from one period to another. While it can be computed for any length of time, the most commonly cited price change in the financial media is the "daily price change", which is the change in the price of a stock or security from the previous trading day's close to the current day's close.
Most economic analysts agree that the simple laws of supply and demand are working and should not cause concern. Speculation in the market has caused an increase in demand, and is the major debate among economists and financial analysts. Since the price per barrel of oil affects gas prices, US consumers are demanding political intervention for relief at the pump.