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A capital gain is a profit that results from a disposition of a capital asset, such as stock, bond or real estate, where the amount realized on the disposition exceeds the purchase price. The gain is the difference between a higher selling price and a lower purchase price. Conversely, a capital loss arises if the proceeds from the sale of a capital asset are less than the purchase price.
Capital gains may refer to "investment income" that arises in relation to real assets, such as property; financial assets, such as shares/stocks or bonds; and intangible assets such as goodwill.
Taxation of capital gain 
Some countries impose a tax on capital gains of individuals or corporations, although relief may be available to exempt capital gains: in relation to holdings in certain assets such as significant common stock holdings, to provide incentives for entrepreneurship, or to compensate for the effects of inflation.
Capital gain in national income accounting 
Capital gains or losses are not counted during National Income accounting as they only pertain to transference of rights to shares and assets and hence do not correspond to any new production activity.
See also