We'll automatically include four quarterly 1040-ES vouchers with your printout if you didn't withhold or pay enough tax this year. We do this to head off a possible underpayment penalty on next year's taxes.
You may get these vouchers if you're self-employed or had an uncharacteristic spike in your income this year. For example, you sold stock or took a large distribution from your retirement plan.
You're not required to make estimated tax payments; we're just suggesting it based on the info in your return. If you feel they're not needed for next year's taxes, you can shred them.