How To Tip Around The World

Dealing with foreign currency is hard enough. There is nothing more vexing than trying to figure out who to tip, how much, and when to tip, especially when you're in a foreign country. The rules of etiquette are different in different countries. We all know that. But what might be not be well known is that the rules of tipping etiquette vary considerably as well. It's a well-known phenomenon that tipping is an expected courtesy in the United States. But does the same apply in other countries?