Having all the info summarized in one page is useful.
> IRAs do not allow access until minimum age 59.5
For a Roth IRA, you can withdraw the contributions, but not the earnings, at any time. For example, if you contribute $5k that gains $100 in interest, you can withdraw the $5k without penalty. If you withdraw the $100, it'll be taxed and penalized.
One source:
> You can withdraw contributions you made to your Roth IRA anytime, tax- and penalty-free. However, you may have to pay taxes and penalties on earnings in your Roth IRA.