In contemporary history, the third millennium is a period of time that most, such as the United States Naval Observatory, claimed began on January 1, 2001, and will end on December 31, 3000, of the Gregorian calendar.Stephen Jay Gould argued that it is not possible to decide if the millennium began January 1, 2000, or January 1, 2001. The Associated Press reported that the third millennium began January 1, 2001, but also reported that celebrations in the US were generally more subdued at the beginning of 2001, compared to the beginning of 2000. This is the third period of one thousand years in the Anno Domini or Common Era.
As this millennium is currently in progress, its first two decades, the past 2000s and the current 2010s, are the subject of the historian's attention. The remaining part of the 21st century and longer-term trends are researched in futures studies.