This was observed in Italy, Poland, Portugal, and Spain. Other Catholic countries followed shortly after, but Protestant countries were reluctant to change, and the Greek orthodox countries didn't change until the start of this century. Thus 2 Sep 1752 was followed by 14 Sep 1752. Different calendars have been developed in various parts of the world, many predating the Gregorian system. The People's Republic of China uses the Gregorian calendar for civil purposes.
Chinese calendar is used for determining festivals.