Over the centuries, the Games have included some wild and woolly sports. Here's how they decide what qualifies to be on the Olympic program.
Imagine you start an Olympics in your own backyard. Deciding what events to include might be simple at first. But if your Olympics grows in popularity, kids from other streets, other neighborhoods, and maybe even other towns will want to join in - and eventually they might want a say in what sports and events are included in the games, and in where they are held.
That's pretty much what happened to the Olympic Games over the centuries as they grew from a simple one-event contest to the huge competition that starts this Friday when 10,500 athletes from 202 countries gather in Athens for two weeks to compete in 28 different sports.
To understand how the Games got to this point, let's look at their ancient origins. And there's no better time to do so than now, when the Olympics have returned to Greece, the birthplace of both the ancient Olympics and the so-called "modern Olympics," first held in 1896.
No one is sure how old the Olympics are, but the first formal records date to 776 BC. Those written logs listed the champions, and the champions only, because the Greeks crowned only winners (with an olive wreath), and never honored second- and third-place finishers.
Just as might occur in a backyard Olympics, the ancient Games began with only one event, a simple footrace. It was about 180 meters, or 200 yards, long - roughly the length of the stadium in Olympia, the traditional site of the ancient Games. This race was the only event in the first 13 Olympics.
A shorter race of about 100 feet was contested by girls in the Heraea, a women's festival that was a form of consolation for women barred from the all-male Olympics (even female spectators were banned under penalty of being tossed from a cliff).
Gradually, over the next few hundred years, the program of the ancient Games, which paid tribute to Zeus, king of the Greek gods, was expanded. Wrestling, boxing, and pankration - a sport that combined the two - were added, as were horse and chariot races.
Mostly, the athletes wore no clothes, except for the chariot drivers and competitors in a warrior-like running event who raced two lengths of the stadium wearing helmets and armor and carrying shields.
Basically, though, things were kept simple, with a focus on track and field.
The ancient Olympics enjoyed a long history of about 12 centuries before Emperor Theodosius of Rome, who came to preside over Greece, abolished the Games in AD 394.
From there, picking up the Olympic trail requires leapfrogging ahead to the 1800s, when a Frenchman, Baron Pierre de Coubertin, an avid if not especially accomplished sportsman, struck on the idea of reviving the Olympics. (Although the most successful, he was not the only one: Evangelis Zappas and William Penny Brookes had each produced earlier Olympics-inspired competitions in Britain.)
The father of the modern Olympics wanted to encourage the physical and mental development of young people by creating an international competition capable of fostering friendship (Coubertin's success in doing so earned him a nomination for the Nobel Peace Prize in 1936). [Editor's note: The original version incorrectly stated that Coubertin won the Nobel, and incorrectly stated the year he was nominated.]
While Coubertin and his fellow organizers created Olympics with echoes of the old, they also wanted Games that reflected the modern world. Thus, in 1896, tennis was on the schedule, along with soccer and cricket, although the latter two were dropped because of lack of entrants - as was rowing because of rough seas. Swimming also was included, although not in a pool. Instead, competitors were delivered to an offshore starting point by boat, only to plunge into the nippy Mediterranean (in April) for their races.
Unlike the ancient Games, which stayed put, the modern ones moved to different world cities. The Olympics of 1900 and 1904 were folded into world fairs in Paris and St. Louis and stretched over months, not weeks, to provide diversion for fairgoers.
As a result, a period of willy-nilly expansion followed. Paris added cricket, croquet, golf, rugby, polo, and tug of war, none of which lasted long. In 1904, St. Louis introduced lacrosse and roque (a variation of croquet), which made short-lived appearances. Four years later, London added motorboating.
The Olympics program, it became clear, needed more consistency. One decision was to create a separate Winter Olympics, beginning in 1924 (figure skating and ice hockey were in the Summer Games before then). Another was to ban sports that relied on motorized propulsion, such as auto racing.
Also, the International Olympic Committee stepped in and nurtured the birth of global governing bodies for each sport. These have helped create a more orderly system for determining which contests end up in the Olympics.
This also led to trials for "demonstration sports," which are given an opportunity to test the Olympic waters in an unofficial capacity - in other words, without awarding medals. Over the years, some of these demonstration sports, such as baseball, have been promoted to permanent status, while others - like football, roller hockey, and korfball - have come and gone.
Having governing bodies for each sport makes it easier to add new events for those sports already in the Olympics. Volleyball, for instance, ushered in beach volleyball in 1996, and cycling introduced mountain biking the same year.
Of course, sports wholly new to the Games occasionally manage to crack the lineup, too, as did table tennis in 1988, badminton in 1992, and softball in 1996.
Softball is for women only, and the International Olympic Committee is keen to find ways to bring greater gender equality to the Games. Women have participated in all but the first modern Olympics, although only in small numbers initially. Now the "playing field" of opportunity is almost level, with about 4,000 female athletes competing this year.
It's tricky to include more women while holding the line on overall participation. To do this, tougher qualifying standards help limit the number of entrants, and certain events or entire sports may be eliminated. At the same time, other sports are clamoring to get in, such as ballroom dancing - and why not, since the Winter Olympics include ice dancing?
As huge as the Olympics have become, the simple sprints, which determine the "world's fastest humans," remain one of its biggest attractions - and the only event on the roster of the very first Olympics.
Sports that you might not associate with Olympic gold were part of the early modern Games. That's because the International Olympic Committee had not yet adopted the criteria that currently require a sport to be played by men in at least 75 countries on four continents (or by women in 40 or more countries on three continents). The sport also had to appear at least twice in an international or continental championship.
• Croquet: In 1896 and 1900, competitors chased glory by knocking wooden balls through wire hoops.
• Jeu de paume: In 1908, this aristocratic French ancestor of tennis featured players in an enclosed court hitting a cloth ball with wooden, spoon-shaped rackets. (It means "game of the palm of your hand.")
• Powerboating: Before the ban on mechanization, it had a short life in 1908.
• Tug of war: The old standby of summer camp and family reunions was a track and field event from 1900 to 1920.