A gratuity (normally called a tip) is a sum of money customarily given by a client or customer to certain service sector workers for the service they have performed, in addition to the basic price of the service. It may or may not be customary to tip servers in bars and restaurants, taxi drivers (including ridesharing), hair stylist and so on, but this depends on the country or location. Giving a tip is typically irreversible, differentiating it from the reward mechanism of a placed order, which can be refunded.