Nominal Gross Domestic Product, or GDP, is a measure of a country's economic output calculated by adding up the total value of goods and services produced in a given period, usually a year or quarter. It is used to assess a nation's economic performance in an average year and measure this performance against other nations. For example, one nation can appear to be more prosperous than another if its nominal GDP is higher.

Unlike real GDP, nominal GDP uses current prices to calculate the value of production. It is important to note that, while nominal GDP takes the cost of goods and services into account, it does not take into account the effects of inflation. This means that an increase in nominal GDP may be due to rising prices rather than an increase in the number of goods and services produced. Hence, a growth in nominal GDP will be distorted if inflation isn't factored into the equation.

To obtain a more accurate reading of a nation's economic performance, economists use a figure called real GDP. Real GDP is derived from nominal GDP, adjusted to reflect fluctuations in prices. It gives an accurate estimate of a nation's GDP at constant prices. This figure takes into account the total output of the economy, while discounting the effects of inflation and other external factors.

Nominal GDP is an important measurement used to assess how well an economy is performing. It provides a good indication of whether certain economic policies are working. For example, governments may use the figure to determine the effectiveness of their fiscal policies. Similarly, investors may use it to analyze the performance of a nation's stock market, as well as its currency. Based on these analyses, investors may decide whether or not to invest in a particular nation.

In conclusion, nominal Gross Domestic Product (GDP) is an important indicator of a country's economic performance. It is calculated by adding up the monetary value of all goods and services produced in a given period. This figure does not adjust for inflation, so it is necessary to use real GDP to evaluate the country’s performance at constant prices and take into account the effects of inflation.