Gains are the output that is over the basic expense of an investment, or the increment of the asset. Selling different assets will result in different gains or losses, which will be charged with different tax rates. For example, the gain from the sale of real property or property held more than one year, will be governed by Internal Revenue Code Section 1231, which is called a “section 1231 gain”. Selling a capital asset will cause a capital gain or loss, which has a different tax rate as well. When there is a gain from the exchanges of the capital assets over the losses, it would be said that the capital gain net income is positive.
See: 26 U.S. Code Part IV - Special Rules for Determining Capital Gains and Losses
[Last updated in June of 2022 by the Wex Definitions Team]