When the gross domestic product is evaluated at the current market prices, it is called the nominal GDP. It includes changes in prices which makes it different from the real GDP. These changes can be due to inflation or price fluctuations. It can be measured in one of three different ways. The "income approach" uses the total of all income from businesses and individuals in a single year. The "expenditure approach" uses the market value of all goods purchased in a single year. The "production approach" is based on the total production in a single year.