system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If the United States adds an extra day every 4 years for Leap Year, China adds a month, and certain other countries approach Leap Year differently, how are we all still in sync with each other in regards to time?
gpt
When you say China adds a month, you're talking about the Chinese calendar. It isn't and never has been in sync with our (Gregorian) calendar. China only uses the Chinese calendar for traditions like Chinese New Year. For government or other official purposes, they use the same calendar as everyone else. 

Countries around the world have many different calendar systems. But everyone uses the Gregorian calendar for official purposes.