A tip is a payment mae to certain service sector workers beyond the advertised price. The amount of a tip is typically computed as a percent of the transaction minus taxes. These payments and their size are a matter of social custom. Tipping varies among cultures and by service industry. Though by definition a tip is never legally required, and its amount is at the discretion of the person being served, in some circumstances failing to give an adequate tip when one is expected would be considered very miserly, a violation of etiquette, or unethical. In some other cultures or situations, giving a tip is not expected and offering one would be considered condescending or demeaning. In some circumstances (such as tipping government workers), tipping is illegal. A tip is sometimes called a gratuity.