The total amount of withholding that they paid. Taxpayers may choose to have their refund directly deposited into their bank account, have a check mailed to them, or have their refund applied to the following year's income tax.
Every year, a number of U.S. taxpayers around the country get tax refunds even if they owe zero income tax.
Contrary to popular opinion, getting a large tax refund is not the best outcome of a tax return; instead it indicates that the individual in effect gave an interest-free loan of the refund amount to the government. Optimally (mathematically), a return should result in a payment owed of just less than would cause a penalty charge. However, some people use the tax refund as a simple "savings plan" where they're pleasantly surprised to get money back each year (even though it is excess money that they paid earlier in the year). Another argument is that it is better to get a refund rather than to owe money, because in the latter case one might find oneself without sufficient money in the checking account to pay the necessary payment.