IRAs (Individual Retirement Accounts) are tax-advantageous savings schemes with a firm focus on building funds for retirement. Any capital gains or dividends from securities held in your IRA are free of tax.
There are 2 types of traditional IRA - deductible and non-deductible.
With a deductible IRA contributions made into the IRA are tax-free, and your taxable income is reduced by the amount of contribution. You qualify for a deductible IRA if 1) if you do not have a retirement plan/401k plan at work or 2) you have a pension plan/401k plan at work, but your adjusted gross income (AGI) is less than a $60000 (for 2006). Note that different rules apply to married couples.
With a Roth IRA, contributions are taxed with the rest of your income, but the fund offers tax-free growth, and furthermore you pay no tax when you make withdrawals in retirement. To be eligible for a Roth IRA your AGI has to below $110000 (for 2006). Again, different rules apply to married couples.
If you earn too much to qualify for either a deductible IRA, or a Roth IRA, a non-deductible IRA is still a reasonable option, as any tax is deferred until you withdraw income in retirement.
IRA funds can be held in a variety of different savings vehicles, from ultra-safe deposits insured by the NCUA, to non-insured stocks and mutual funds. Watch out for IRA administrators with a poor investment record and high fees.