Where are you at in the world? You're going to want to do research on capital gains if you're in the US. From https://turbotax.intuit.com/tax-tools/tax-tips/Investments-and-Taxes/Guide-to-Short-term-vs-Long-term-Capital-Gains-Taxes--Brokerage-Accounts--etc--/INF22384.html
Short-term capital gains
Short-term capital gains do not benefit from any special tax rate –
they are taxed at the same rate as your ordinary income. For 2016,
ordinary tax rates range from 10 percent to 39.6 percent, depending on
your total taxable income.
If you sell an asset you have held for one year or less, any profit
you make is considered a short-term capital gain. The clock begins
ticking from the day after you acquire the asset up to and including
the day you sell it.
Long-term capital gains
If you can manage to hold your assets for longer than a year, you can
benefit from a reduced tax rate on your profits. For 2016, the
long-term capital gains tax rates are 0, 15, and 20 percent for most
taxpayers. If your ordinary tax rate is already less than 15 percent,
you could qualify for the zero percent long-term capital gains rate.
If you're not buying and holding onto the asset for over a year, you need to treat all gains/losses as normal income when it comes time to do taxes.
Each state may have different tax laws as well.