For some travelers, it's the most stressful part of the holiday - the bill arrives, you pay, but how much should you leave for the frankly unexceptional service you've received?
In Europe, probably nothing, according to a guide published by air fare search site Cheapflights.com this week.
Service is always included in France, for instance, while many restaurants in the UK and Ireland will include a service charge whether you like it or not and even in Italy, Spain or Portugal, tipping is not expected unless the service is exceptional.
However, across the pond it's a different world, says Cheapflights.com, with tips standard in Canada and "expected" in the US - 20 percent for a meal, $1 per drink in a bar and $5 for a hotel concierge who offers information.
In Asia, tips aren't necessary in China, Japan or Singapore, but will be appreciated in Hong Kong, Manila and Bangkok.
In most parts of the Middle East, South America and Africa, tipping is customary, although generally for less than in North America.
Earlier this year, a TripAdvisor survey found that 80 percent of Spaniards said that they do not always tip on holiday, followed by 78 percent of Italians, 76 percent of French and 57 percent of Britons.
Perhaps this is down to the lack of research on tipping - although the following links are useful for more information, if in doubt, adding ten percent is probably the course of action least likely to cause offense or embarrassment.
Cheapflights.com Top 10 Tips for Tipping http://news.cheapflights.com/2010/07/top-10-tips-on-tipping-around-the-world/
Condé Nast Traveler's Tipping Guide: http://www.concierge.com/cntraveler/articles/500117
Travel + Leisure's Worldwide Guide to Restaurant Tipping http://www.travelandleisure.com/articles/worldwide-guide-to-restaurant-tipping/1
Magellan's Worldwide Tipping Table http://www.magellans.com/store/article/367Reuse content