Other courses quickly followed suit, and by the 1870s, 18 holes had become the norm. According to one version, the number 18 was suggested by a St. Andrews old-timer who saw that it took precisely 18 shots to drink a fifth of scotch—-one shot for each hole. The man's son hated whisky, so he passed this trait on to other generations of golfers.
A more plausible explanation comes from an American golfer named E. D. Adams. He introduced the idea of a "whole course" in 1884, and his courses usually consisted of an eighteen-hole layout with one starter's kit per person. This idea really took off after World War II, when more affordable clothing became available that allowed men to play golf in outfits instead of tuxedos.
Today, you can buy complete sets of golf equipment at many retail stores, including Amazon, eBay, and Walmart. These sets typically include a driver (the club used for hitting the ball), two hybrids (used during short shots between holes or upon recovery from mishits), two irons (for long shots), a putter, and other items such as gloves and a bag.
Golf has become very popular in America. In fact, some people say that it is becoming too popular because no one can afford to play anymore.
One of the members at Andrews in 1858 pointed out that it takes precisely 18 shots to finish down a fifth of Scotch. By limiting himself to one shot of Scotch every hole, the Scot concluded that a round of golf was completed when the Scotch ran out. This member of the club's committee then proposed that they play a full round of 18 holes even if there was still some Scotch left. This must have been quite a sight - these aristocratic men playing rough American sports - digging ditches, sawing trees up into firewood, throwing rocks at targets - and drinking together after their games.
The first official men's professional tournament was held in 1860 at New York's Golf Club. It was an event that lasted only one year but it set a precedent for future tournaments. In 1861, another pro-am started things off again with a new tournament in Philadelphia. These events proved so popular that more soon followed. In 1866, a national championship was created when the leading players on the amateur circuit met at Prince's Golf Club in Brooklyn and voted to make their title official. The winner of this annual match play contest would be known as "the champion".
Through most of its history, golf has been played by men who were either amateurs or professionals. Amateurs were not supposed to earn money from playing golf but rather we mean them when they say "it's not what you earn, it's how you live".
According to Scottish Golf History, the number was reduced to 18 quite randomly in 1764 when four short holes were consolidated into two (played in two directions). The reason for this reduction is not known for certain, but it may have been because the game became too difficult to be worth playing for large prizes. It is possible that the number 18 represents the maximum number of balls that could be used up without going back to the bag.
Golf has always been a more leisurely sport than other major sports like football or baseball. As such, it's natural that it would want to limit itself to a single round rather than divide itself into three- or five-day events like those other sports do.
It also helps explain why there are only so many great shots in golf. If you can make a shot on one hole, then you've made a shot on all holes. There are no leftovers, so to speak. A player who hits very long drives but misses most of the rest of their shots will usually finish with a lower score than someone who makes every shot except the long ones. Long drives are exciting and fun to watch, but they don't add any points to your total score. They're just rolls of the dice.