Flame and Torch
The ancient Greeks believed that fire was given to mankind by Prometheus, and considered fire to have sacred qualities. Eternal flames burned in front of Greek temples, flames lit using the rays of the sun. Greek rituals also included torch relays, although this was not actually part of the ancient Olympic Games.
The Olympic flame is lit in front of the ruins of the Temple of Hera in Olympia, emphasizing the connection between the ancient Games and the modern Games. An actress playing a high priestess uses a parabolic mirror to focus the rays of the sun, igniting a flame. (In case of cloudy weather, a backup flame is lit in advance.) A long relay of runners carrying torches brings it to the site of the Games. There, the final torch is used to light a cauldron that remains lit until it is extinguished in the Closing Ceremony.
The first such relay took place for the 1936 Berlin Games. 3,331 runners brought the flame through Greece, Bulgaria, Yugoslavia, Hungary, Austria, Czechoslovakia, and Germany. Similar relays have taken place for every Summer Games since. The 2004 relay is the first to start and end in Greece; it is also the first to visit every continent, crossing 34 cities in 27 countries before returning to Greece. The flame travels by plane between cities, and is relayed by foot within cities. Being a torch-bearer is considered an honor, one often given to local residents with a record of community service, in addition to athletes and celebrities. The torches generally burn a gas fuel, and are specially designed to resist the effects of wind and rain.
Since 1964, the Winter Games have also had a torch relay starting in Olympia. Of the three immediately preceding Winter Games, two (1952 and 1960) had torch relays starting in the fireplace of skiing pioneer Sondre Norheim, and one (1956) had a relay starting in Rome. The 1984 Winter Games were preceded by two torch relays, one from Norheim's fireplace, and the other from Olympia. The plan had been to mingle the two flames, lighting the cauldron with the combination, but this was disallowed; instead, only the Greek flame was used.
Release of Doves
After the cauldron is lit, doves are released, as a symbol of peace. This was first done in the 1896 Olympics, and then in the 1920 Olympics. Since 1920, this has been an official part of the Opening Ceremony of the Summer Games. They are generally not released during the Winter Games, because it's too cold for the birds, but symbolic substitutions are sometimes used. In the 1994 Winter Games, for example, white balloons were released.
The order—first lighting the cauldron, then releasing the doves—is important. In the 1988 Seoul Games, they tried it the other way around. Unfortunately, many of the doves were in the area of the cauldron just before it burst into flames, leading to their unexpected demise.
The Olympic Oath
The Olympic Oath is taken by one athlete and one judge from the home nation during the Opening Ceremony of every Olympics, acting on behalf of all the competitors and judges. Since 1984, this has been taken while holding a corner of the Olympic flag. Until then, the national flag of the home nation was used.
The oath was first taken by an athlete in 1920. Originally, this was primarily a declaration that all the athletes were amateurs. The wording has been revised considerably over the years, however; amateurism is no longer a general requirement, and a specific reference to doping was added in 2000. The current form is "In the name of all the competitors I promise that we shall take part in these Olympic Games, respecting and abiding by the rules which govern them, committing ourselves to a sport without doping and without drugs, in the true spirit of sportsmanship, for the glory of sport and the honor of our teams."
The oath was first taken by a referee in 1972. The current form of that oath is "In the name of all the judges and officials, I promise that we shall officiate in these Olympic Games with complete impartiality, respecting and abiding by the rules which govern them, in the true spirit of sportsmanship."