In the United States, taxes on the stocks are changing depends on the account type, receiving dividends and income level.
If you buy stocks for your retirement account, you pay no any tax until the retirement. On the other hand, the stocks outside retirement accounts are taxable, for example if you accept dividend payments in the year you are, you will pay a tax rate of %15 at the end of each year. In addition, if your taxable income is more than $415,050, or $466,950 for married couples, your tax rate for stocks will be 20%.
Also, if you sell the stock, you will pay a tax rate of 15%, or 20% if you are in high income level, for any profit you made over time. This kind of tax is called capital gains tax. There is an one exception for this tax. If you hold the stock less than one year and sell the stock, you will pay your regular tax rate, which is probably higher than capital gains tax rate.