GDP adjusted for inflation to reflect the real value of goods and services is called real GDP.
Nominal GDP measures output using prices from the period being reported, so it can rise simply because prices increased. Real GDP removes the effect of price changes by valuing output with constant or chain-linked prices, making it more useful for judging changes in the quantity of production.
The distinction matters when comparing economic performance across years. If nominal GDP grows by 6% while prices rise by 4%, real output has grown by less than the nominal figure. Statistical agencies use different base-year or chain-weighting methods, so real GDP figures can be revised as better data become available.
Real GDP should not be confused with the GDP deflator. Real GDP is an inflation-adjusted output measure; the GDP deflator is a price index calculated from the relationship between nominal and real GDP. Nominal GDP, by contrast, is measured at current prices.