But the opportunity and obligation to offer gratuity abounds, and you may be surprised to learn that you’re tipping all wrong. In fact, many people don’t even understand the full equation when it comes to gratuity, says Jodi R. R. Smith, an etiquette consultant and author of The Etiquette Book: A Complete Guide to Modern Manners, $19.28 at Books-A-Million. (Get Books-A-Million coupons.)

“Most people tip because they want to reward a job well done—and that is certainly part of the process,” Smith says. “But tips are also to ensure that the service provider is adequately compensated for their time and efforts. And most people don’t also realize that tips are an insurance policy on good service going forward.”