Inventory investment is a component of gross domestic product (GDP). What is produced in a certain country is naturally also sold eventually, but some of the goods produced in a given year may be sold in a later year rather than in the year they were produced. Conversely, some of the goods sold in a given year might have been produced in an earlier year. The difference between goods produced (production) and goods sold (sales) in a given year is called inventory investment. The concept can be applied to the economy as a whole or to an individual firm, however this concept is generally applied in macroeconomics (economy as a whole). Unintended unsold stock of goods increases inventory investment.