The Olympics logo hangs above visitors to London. Credit: Corbis Images

For even the most seasoned Olympics observer, understanding changes to the games from one Olympics to the next can be a challenge. The International Olympic Committee (IOC), the supervisory body that governs the Summer and Winter Olympics, decides the competition’s program years in advance. So here’s what’s new with this year’s Summer Olympics in London.

Baseball and softball didn’t make the cut.

One of the biggest changes from the 2008 Summer Olympics in Beijing is the exclusion of two sporting events: baseball and softball. The decision to eliminate both sports was made by the IOC during a meeting in Singapore in 2005. The decision came down to a vote on which of the then-28 sports would remain in the Olympic program. Baseball and softball failed to secure enough support to remain Olympic events.

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This Olympics will be the first to remove events from the program since 1936. Both sports will also not be present at the 2016 Summer Olympics in Rio de Janeiro, Brazil. They are, however, eligible to return to the games, but not until 2020.

Women’s boxing and tennis mixed doubles are added for 2012.

For the first time in Olympic history, women will be boxing at the Olympics in three weight classes: flyweight, middleweight, and lightweight. Three women qualified to represent the United States in London, joining the nine men on the national boxing team.

In 2009, the IOC decided to revive mixed doubles in tennis for the 2012 games. The last time mixed doubles was an official event was for 1924 Summer Olympics in Paris. Although some of the sport’s biggest stars — including Roger Federer, Novak Djokovic, and Maria Sharapova — have opted out to focus on other events, others, such as Serena Williams and Andy Roddick, are competing in the event, according to Fox News.

Squash and karate nearly made the program.

Just as the Olympic program can be condensed to remove events, it can also be expanded with additional sports. Advocates from sporting associations lobby the IOC for the inclusion of the event in the Olympics.

Two female boxers fight in a practice event ahead of the Olympics. Credit: Getty Images

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In 2005, squash and karate received enough votes to be considered for the program for the 2012 games and beyond. In a final confirmation vote, however, neither sport garnered enough support to make it official.

Other sports that were in contention for inclusion in 2012 were golf, roller sports, rugby, and wake boarding. In 2009, golf and rugby were approved as future events, beginning with the 2016 Olympics. Both sports had previously been eliminated from the Olympic program, golf after 1904 and rugby after the 1924 Olympics.

Saudi Arabia, Brunei and Qatar will field female athletes for the first time.

For the first time in Olympics history, every nation participating in the games will field at least one female athlete. Saudi Arabia, Brunei, and Qatar had been the only holdouts.

Qatar and Brunei were the first to determine that they would have women representing their countries at the 2012 games. One of the four women Qatar is sending to London will be the flag-bearer in the Olympic parade.

Following a wave of criticism against Saudi Arabia’s policy of banning women from entering the Olympics, the kingdom relented and will enter two female athletes, who will compete in judo and track and field.

Some 42 percent of athletes competing at the games four years ago in Beijing were women. At the 1908 games, that number was 1.8 percent, according to Voice of America.

Kosovo and South Sudan will not field teams at the Olympics.

The two newest countries on the global stage, Kosovo and South Sudan, will have to wait until at least 2016 to field national teams.

Marathoner Guor Marial, a native of South Sudan who has been living in the United States for more than a decade, will be competing in the Olympics, but since he doesn’t hold a South Sudanese passport, and will not run for Sudan, the olympic Committee is allowing him to enter as an independent. He’ll wear a uniform associated with no particular country, and, should he medal, an Olympic hymn will play. Kosovo’s best chance for an Olympic entry, Majlinda Kelmendi, will be competing for Albania because the IOC doesn’t yet recognize Kosovo.