A capital gain is the difference between what you paid for an investment and what you received when you sold that investment. If you made a profit on the investment, then you have a capital gain. If you lost money on the investment, then you have a capital loss.
Investments include mutual funds, bonds, stocks, options, precious metals, real estate, and collectibles.
For e.g. when you sell an asset at a higher price than you paid for it, the difference is your capital gain. For example, if you buy 100 shares of stock for $20 a share and sell them for $30 a share, you realize a capital gain of $10 a share, or $1,000 in total.
If you own the stock for more than a year before selling it, you have a long-term capital gain. If you hold the stock for less than a year, you have a short-term capital gain.
Most long-term capital gains are taxed at a lower rate than your other income while short-term gains are taxed at your regular rate. There are some exceptions, such as gains on collectibles, which are taxed at 28%. The long-term capital gains tax rates are 15% for anyone whose marginal federal tax rate is 25% or higher and 5% for anyone whose marginal rate is 10% or 15%.
You are exempt from paying capital gains tax on profits of up to $250,000 on the sale of your primary home if you're single and up to $500,000 if you're married and file a joint return, provided you meet the requirements for this exemption.