A traditional IRA is a tax-deferred retirement savings account. You pay taxes on your money only when you make withdrawals in retirement. Deferring taxes means all of your dividends, interest payments and capital gains can compound each year without being hindered by taxes - allowing an IRA to grow much faster than a taxable account.
Traditional IRAs come in two varieties: deductible and nondeductible. Whether you qualify for a full or partial tax deduction depends mostly on your income and whether you have access to a work-related retirement account like a 401(k).