Capital Gain
The profit when you sell an asset for more than you paid; taxed at different rates depending on how long you held it.
A capital gain is the profit from selling an investment or asset for more than its cost basis (what you paid, plus certain adjustments). If you sell for less, you have a capital loss, which can offset gains.
How long you held the asset determines the tax. Assets held a year or less produce short-term capital gains, taxed at your ordinary income rate. Assets held more than a year produce long-term capital gains, taxed at preferential rates (0%, 15%, or 20% federally depending on income) — a major reason long-term investing is tax-favored.
Realized gains raise your taxable income and MAGI, which can ripple into ACA subsidies and Medicare IRMAA. The 0% long-term rate at lower incomes also creates planning opportunities to harvest gains cheaply in low-income years.
This definition is general information to help you understand a term, not financial, tax, or legal advice. Figures that change year to year (limits, thresholds, rates) should be confirmed against current official sources. For guidance on your situation, a licensed fee-only fiduciary is the right next step.