Flags
Each counry has a flag. The coutry's uniforms are usually based off of the flag's colors. For instance, the U.S.'s uniforms always have red white and blue except the swimming suits. At the openning ceremonies one of the athletes carry the flag of their country. It is an honor to carry the flag of your country at the openning ceremonie.
Germany: yellow, black, red
U.S.: red,white, blue
New Zealand: red,white,blue
China: red, yellow
Mexico: red, white, green
Sweeden: yellow, blue
Spain: yellow, red
Japan: red, white
Brazil: green, yellow, blue
Russia: red, white, blue
Taiwan: red,white,blue
Egypt: red, white, black
Israel: blue,white
Thailand: red, white, blue
Canada: red, white