Like all other types of investments, IRAs have the potential to grow over time. The two main ways an IRA can grow are through annual contributions and investment appreciation. However, there are limits to the annual contribution amounts allowed and not all investments are successful in the long term. Roth IRAs make a profit through capitalization, which helps your money grow more quickly.
Whenever your investments generate dividends or increase in size, that amount goes toward your account balance. Then you make a profit with those returns, and so on. That means that your money will continue to grow regardless of whether you contribute extra money or not. In this way, Roth IRAs are the opposite of traditional tax-deferred or 401 (k) IRAs; with those accounts, you'll have to pay taxes when you withdraw the funds.