When you contribute to a Roth IRA, it's with the intention of letting that money grow tax-free for retirement. Because it's an after-tax contribution, the IRS says you can take withdrawals at any time. However, since this is your retirement fund, there are some rules about withdrawal eligibility depending on what age you are and how long you've had your Roth.
At age 59 ½, you can withdraw contributions from your account at any time without being subject to the 10% early withdrawal penalty. You will still have to pay taxes on this money as regular income, however. For example, if you contributed $5900 one year and wanted to withdraw all of it the next year, you would be taxed as though it was an additional $590 of your income that year.