The Times Square New Year's Eve Ball begins dropping at 11:59pm as people count down the final seconds before the new year. People have celebrated New Year's Eve in Times Square since 1904. The idea of dropping balls to symbolize passing time originated in England.
We use the Gregorian calendar, decreed by Pope Gregory XIII in 1582. Catholic countries adopted the calendar first. It is now international. The secular CE and BCE are used, meaning Common Era and Before the Common Era. Jesus is said to have been born in 4 BC. AD (Anno Domini) is Latin for "In the year of our Lord."