According to some sources, the word “tips” is actually an acronym—it's short for “To Insure Prompt Service,” and the list of people who are commonly tipped—at least in the United States—includes everyone from hair and nail salon workers to bellhops, cab drivers, newspaper delivery people, porters, valets, bartenders, and, of course, restaurant wait staff.
As multifamily housing became the norm in densely populated urban areas like New York City, building staff joined the tip list. From the doorman who greets you, signs for packages, and keeps an eye out for your safety to the super or handyman who doesn’t grumble (much) about being called to deal with a leaky steam-pipe at the crack of dawn on a Sunday morning, building staff work hard 24/7 to make things easier and more convenient for you as a resident. When the holidays roll around, it’s simply good manners to show your staff a gracious gesture of thanks for a job well done.
It’s not unreasonable to ask why we tip at all in the United States—plenty of other countries don’t do it, and after all, keeping the boiler running and helping residents out is the building engineer’s job—he gets a salary already, right?
The origin of tipping is interesting, though perhaps not exactly gracious. Though there is some disagreement, most historians agree that the practice likely began during the heyday of the Roman Empire with rich, landowning Roman citizens tossing a few coins to the peasants as a conspicuous gesture of wealth and largesse. It has also been suggested that “tipping” was the term used by feudal lords in Medieval Europe to describe their practice of throwing the occasional piece of gold to their serfs as they passed on horseback; the noblemen felt that the gold appeased the rabble and assured them safe passage through the crowd. (No word on how the serfs felt about it.)
Though noblemen and ladies no longer ride through the streets on horseback, casually tossing doubloons to the ragged masses (they mostly use Lincoln town cars these days, and thanks to the recession keep what doubloons they have left in offshore accounts), the practice of tipping has stayed with us.