An international district is a special district where you can meet people from any server. For example if you connect to the American territory, in your normal districts (home districts) you can only see people from the American server. If you go to an international district you can meet with people from any territory.
This is useful for several reasons:
- It means that you can meet up with friends for all over the world and form a group
- You can trade items with someone from a different territory
- The Frog is most commonly found in the international districts of Lion's Arch
One unfortunate thing about the first point is that you cannot meet in one of the international districts of The Temple of the Ages to form a group to go to the Underworld or Fissure of Woe because you will never have Favor of the Gods.