Introduction:
Tipping is a practice that varies across different countries and cultures. While it is considered a norm in some countries, it is seen as insulting in others. This makes tipping a contentious and controversial issue.

Contentious:
Tipping can be described as contentious because it generates a lot of disagreement and controversy. Different people have contrasting views on whether or not to tip, how much to tip, and who to tip. The practice of tipping can often lead to heated debates and arguments, as there is no universally accepted standard for tipping.

Controversial:
Tipping is also controversial because it raises questions about fairness and equity. Some argue that tipping allows customers to reward good service, while others believe it creates an unequal system where waiters depend on tips to make a living wage. The controversy surrounding tipping has led to debates about whether it should be abolished or replaced with fairer alternatives, such as higher wages for service industry workers.

Cultural Differences:
The difference in tipping norms across countries is largely influenced by cultural factors. In some cultures, tipping is seen as a way to show gratitude and appreciation for good service. In these countries, not tipping may be considered rude or disrespectful. On the other hand, in cultures where tipping is not customary, leaving a tip may be seen as an insult or implying that the service was inadequate.

Examples:
- In the United States, tipping is considered a norm and is expected in most establishments. It is customary to tip waiters around 15-20% of the total bill.
- In Japan, tipping is not a common practice and may even be seen as rude. The Japanese believe that good service is the standard and should not be rewarded with extra money.
- In France, a service charge is typically included in the bill, so tipping is not necessary. However, leaving a small amount of change as a gesture of appreciation is common.

Conclusion:
The practice of tipping waiters varies across different countries and cultures, making it a contentious and controversial issue. The differing views on tipping reflect cultural norms and beliefs about fairness and gratitude. Understanding these cultural differences is important when traveling to different countries to avoid unintentionally insulting or disrespecting waitstaff.

The word must describe the issue of tipping. The context says that in some countries, tipping is considered a standard practice whereas in some others it is an insult. The word in the blank must describe this conflict or difference in opinion.