Popular culture holds the year 2000 as the first year of the 21st century and the 3rd millennium due to a tendency of grouping the years according to decimal values, as if year zero were counted. According to the Gregorian Calendar, these distinctions fall to the year 2001, because the 1st century was retroactively said to start with year AD 1. Since the calendar does not have year zero, its first millennium spanned from years 1 to 1000 inclusively and its second millennium from years 1001 to 2000. (See more at Century and Millennium.)
The year 2000 is sometimes abbreviated as "Y2K" (the "Y" stands for "year", and the "K" stands for "kilo" which means "thousand"). The year 2000 was the subject of Y2K concerns, which are fears that computers would not shift from 1999 to 2000 correctly. However, by the end of 1999, many companies had already converted to new, or upgraded, existing software. Some even obtained Y2K certification. As a result of massive effort, relatively few problems occurred.
February 29 – A rare century leap year date occurs. Usually, century years are common years due to not being exactly divisible by 400. 2000 is the first such year to have a February 29 since the year 1600, making it only the second such occasion since the Lilian rule was introduced in the late 16th century. The next such leap year will occur in 2400.
April 22 – In a predawn raid, federal agents seize 6-year-old Elián González from his relatives' home in Miami and fly him to his Cuban father in Washington, D.C., ending one of the most publicized custody battles in U.S. history.
Pakistani authorities announce that their police have found an apparently ancient mummy of a Persian Princess in the province of Balochistan. Iran, Pakistan and the Taliban all claim the mummy until Pakistan announces it is a modern-day fake on April 17, 2001.
The New York Yankees defeat the New York Mets 4-2 in the fifth game of the World Series to win the first "Subway Series" since 1956 by 4 games to 1. The series win was the Yankees third in a row and 26th overall.[importance?]