For the 2004 Athens Games, the International Olympic Committee (IOC) recognized 202 member nations, all but one of which -- Djibouti -- participated. Since then, three National Olympic Committees (NOCs) have been admitted to the Olympic family: the Pacific island nations of Tuvalu (TUV) and the Marshall Islands (MHL), and the former Yugoslavian republic of Montenegro (MNE).

Pedrag Jokic, seen here representing Serbia and Montenegro at the 2005 Worlds, is now part of independent Montenegro's Olympic water polo team.
All 205 current member nations are expected to compete in Beijing, when China will become the third Asian host of the Summer Games. The 1960 Olympics were held in in Tokyo, Japan. In 1988, the setting was Seoul, South Korea.
Of those 205 countries, 87 will be seeking their first Summer Olympic medals. Three participants in Athens saw their flag raised at a medal ceremony for the first time: Eritrea, Paraguay and the United Arab Emirates.
In the past 20 years, participation at the Games has increased significantly:
The issue of which countries have competed at every Games of the Olympiad is a contentious one, open to historical interpretation. It has engaged Olympic historians and journalists alike as the status of the Games has grown and entered into the academic realm. Upon considering politics, records and technicalities, the answer ranges anywhere from two countries (Australia, Greece) to five countries (Australia, France, Great Britain, Greece, Switzerland).