Greece's delegation always enters first during the Parade of Nations at each Olympics; their perpetual leading spot shows respect to their history as the site of the first Olympics in ancient times. The end spots always follow a form as well. The second-to-last spot goes to the nation up next to host the Games, and the current host nation enters last to close the Parade of Nations. Except for the spots mentioned above, the rest of the nations usually enter in alphabetical order corresponding to the host nation's language.

Source: Time