Be quiet Tibby, you're Canadian. You don't know what you're talking about. It's not free money. It's MY money.
A Tax refund (or return) is a check a taxpayer receives from the federal government (state too, but to a lesser extent). Most employers retain a portion of each paycheck (weekly, monthly, whatever) and send it to the feds for income taxes on behalf of the employee.
At the end of the year, the feds may have, for example 35% of the income that I earned. Then, when I process my taxes, it may turn out that I only owed the feds 25% of my income, so I am entitled to receive back the difference - 10%. This is the tax return. It's money that the feds received throughout the year that did not belong to them. It's not stealing; the taxpayer can decide how much to give them.
Each taxpayer can adjust how much their employer withholds (if any), but is responsible to pay whatever is owed at the end of the year. Some people, like dalf, did not pay enough throughout the year, and so owe more money at the end of the year. Some people, like Outlaw Torn, pay too much throughout the year and get back a large sum. Most taxpayers are accustomed to having a certain amount withheld, and their payceck take home pay is what they work with each month, so their tax return feels like a bonus (free money, as you put it), even though it's really income they earned but gave to the feds in excess.