Why Do People Around the World Celebrate New Year on January 1st?

Imagine your day is divided into chunks, like pieces of a puzzle. Some people use chunks that are based on the moon, they're called lunar calendars. But January 1st comes from a calendar that uses the sun instead, and it started in ancient Rome. Over time, this date became a special day when everyone celebrates the start of the year, even if not all of them follow the same type of calendar.