A millennium (pl millennia) is a period of Time equal to one thousand Years (from Latin la mille, thousand and la annum The first millennium is a period of time that commenced on January 1, 1, and ended on December 31, 1000, of the Julian calendar.A century (from the Latin centum, meaning one hundred is One hundred consecutive Years Centuries are numbered ordinally (eThe 1st century BC started the first day of 100 BC and ended the last day of 1 BC.The 1st century was the Century that lasted from 1 to 100 according the Julian calendar.The 2nd century is the period from 101 to 200 in accordance with the Julian calendar in the Christian / Common Era.See also List of centuries, History This is a list of Decades in history including links to corresponding articles with more information about themNote Sometimes the ' 30s is used as shorthand for the 1930s, the 1830s, or other such decades in various centuries Events and TrendsNotes Sometimes the ' 40s is used as shorthand for the 1940s, the 1840s, or other such decades in various centuriesNote Sometimes the ' 50s is used as shorthand for the 1950s, the 1850s, or other such decades in various centuries Events and TrendsYear 20 was a Leap year starting on Monday (link will display the full calendar of the Julian calendar.Year 21 was a Common year starting on Wednesday (link will display the full calendar of the Julian calendar.Year 22 was a Common year starting on Thursday (link will display the full calendar of the Julian calendar.This article is about the year AD 23 For other uses see 23 (number, 23 (numerology, or 23 (disambiguation.Year 24 was a Leap year starting on Saturday (link will display the full calendar of the Julian calendar.Year 25 was a Common year starting on Monday (link will display the full calendar of the Julian calendar.Year 26 was a Common year starting on Tuesday (link will display the full calendar of the Julian calendar.Year 27 was a Common year starting on Wednesday (link will display the full calendar of the Julian calendar.Year 28 was a Leap year starting on Thursday (link will display the full calendar of the Julian calendar.Year 29 was a Common year starting on Saturday (link will display the full calendar of the Julian calendar.The 1920s is sometimes referred to as the " Jazz Age " or the " Roaring Twenties " when speaking about the United States and CanadaEvents and trends Nationalistic independence helped reshape the world during this decade Greece gains independence from the Ottoman EmpireTiberius Julius Caesar Augustus (or Tiberius I) born Tiberius Claudius Nero (November 16 42 BC – March 16 AD 37) was the second RomanThe Roman Emperor was the ruler of the Roman State during the imperial period (starting at about 27 BCYear 37 was a Common year starting on Tuesday (link will display the full calendar of the Julian calendar.