Shortly after the beginning of the Olympics Opening Ceremony, the Parade of Athletes occurs where the athletes enter the stadium by country. It usually seems to be alphabetical, but some countries are out of order. How is it determined which order the teams are in when they enter the stadium?
During the Parade of Athletes, the first team to enter the stadium is always Greece, in honor of the fact that the Olympics has its origin in ancient Greece. The last team in is the host country. The rest of the teams enter the stadium in alphabetical order, according to the language of the host country. This is why teams are in a different order in each Olympics.
In 2004, when the Olympics were held in Athens, Greece, the Greek flag bearer, weightlifter Pyrros Dimas, entered the stadium first alone, leading the parade. The rest of the Greek athletes entered as the last team in the parade.
The International Olympic Committee has published a factsheet outlining the elements of the opening ceremony.