A tip (also called a gratuity) is an amount of money given as gratitude to somebody who has provided a service. It is normally in addition to any fee that is charged. It is a custom in many societies. For example, after people finish eating dinner at a restaurant, even after they have paid the bill for the food, they leave some extra money on the table to thank the server.
Tipping and the amount of money that people give as tips varies between countries. In some locations tipping is discouraged and considered insulting. In other locations tipping is expected from customers. The tip can be a specific range of money or a percentage of the bill, such as 15 percent or 20 percent. In some circumstances, such as with government workers in some areas, giving tips is against the law. Some restaurants charge a service charge and add it onto the bill. In this case, you do not have to leave a tip. For many service workers, like servers, bartenders, and taxi drivers, tips are an important part of their income.