Simplify the following text for a Grade 13 native English-speaking person.
Original: While not an official observance , a number of cities and regions in the United States , France , England , Africa , Italy , China , Korea , Vietnam , India , and Thailand have notable celebrations .
Simplified: Many cities and regions in the United States , France , England , Africa , Italy , China , Korea , Vietnam , India , and Thailand have notable celebrations of World Party Day ( P-Day ) .