Who to tip? How much?

These are questions that go back generations.

At the end of the 19th century, it was a huge controversy.

“There was probably not a newspaper you could pick up or a magazine that you could pick up, in the late 19th and early 20th century, and flip through it for a few pages, and not find an article about tipping,” said Andrew Haley, a history professor at the University of Southern Mississippi, and author of “Turning the Tables: Restaurants and the Rise of the American Middle Class.”

Middle class diners wrote editorials against tipping. They boycotted. Some places outlawed it.

“Six states passed anti-tipping laws in the early 20th century,” Haley said, “and at least four other states were considering similar laws.”

Over time, Americans got used to tipping and settled on some basic rules.

“The norm is very clear,” said Mike Lynn, a marketing professor at Cornell University School of Hotel Administration, “you tip 15 percent to 20 percent to waiters and waitresses.” That, he says is pre-tax, and it includes beverages and wine.