Significance of Jesus's birth on the Gregorian calendar

The Gregorian calendar, used globally, reset based on the year of Jesus Christ's birth. Prior to that, there were more years in existence. The date convention entails BC (before Christ) and AD (Anno Domini), indicating 'the year of our Lord' in medieval Latin. Jesus's birth marked a significant event, changing the course of time and resetting the calendar, a unique occurrence as it acknowledges the extraordinary nature of Jesus's birth in the Middle East over 2,000 years ago.