A millennium (plural millennia or millenniums) is a period equal to 1000 years,[1] also called kiloyears. It derives from the Latin mille, thousand, and annus, year. It is often, but not always, related to a particular dating system.

Sometimes, it is used specifically for periods of a thousand years that begin at the starting point (initial reference point) of the calendar in consideration (typically the year "1"), or in later years that are whole number multiples of a thousand years after it. The term can also refer to an interval of time beginning on any date. Frequently in the latter case (and sometimes also in the former) it may have religious or theological implications (see millenarianism).

Counting years

There are two methods of counting years: current years (the count begins at the epoch) and elapsed years (the count is of completed years since the epoch). This latter method is used in India.


The original method of counting years was ordinal,[citation needed] whether 1st year AD or regnal 10th year of King Henry VIII. This ordinal numbering is still in the names of the millennia and centuries, for example 1st millennium or the 10th century, and sometimes in the names of decades, e.g., 1st decade of the 11th century.


The main issues arise from the content of the various year ranges. Similar issues affect the contents of centuries. Decades are usually referred to by their leading numbers: the decade called 1990s would by its naming not include 2000. Similarly the century called the 1900s includes 1900 but not 2000.

Those following ordinal year names naturally choose

  • 2001–2100 (inclusive) as the current century
  • 2001–3000 (inclusive) as the current millennium

Those who are influenced by the leading digit equally naturally choose

  • 2000–2099 (inclusive) as the current century
  • 2000–2999 (inclusive) as the current millennium

Debate over millennium celebrations

The Gregorian calendar has been defined with counting origin 1. Thus each period of 1,000 years concludes with a year number with 3 zeroes, e.g., the first thousand years in the Western calendar included the year 1000. However, there are two viewpoints about how millennia should be thought of in practice. One viewpoint relies on the formal operation of the calendar, while the other appeals to popular culture. Stephen Jay Gould argued that the choice is arbitrary, and since the question revolves around rules made by people, rather than a natural phenomenon that is subject to experimental measurement, the matter cannot be resolved.[2]

The ISO 8601, employed in a number of contexts, uses the astronomical calendar, in which year counting starts at 0. Thus, when using this calendar, the millennium starts at x000 and ends at x999. There was a popular debate leading up to the celebrations of the year 2000 as to whether the beginning of that year should be understood (and celebrated) as the beginning of a new millennium. Historically, there has been debate around the turn of previous decades, centuries, and millennia.

The issue is tied to the convention of using ordinal numbers to count millennia (as in "the third millennium"), as opposed to "the two thousands", which is unambiguous as it does not depend on which year counting starts. The first convention is common in English speaking countries, but the latter is favored in for example Sweden (tvåtusentalet, which translates literally as the two thousands period).

Viewpoint 1: x001–y000

Those holding that the arrival of the new millennium should be celebrated in the transition from 2000 to 2001 (i.e., December 31, 2000 to January 1, 2001), argued that because the Gregorian calendar has no year zero, the millennia should be counted from 1 AD. Thus the first period of one thousand complete years runs from the beginning of 1 AD to the end of 1000 AD, and the beginning of the second millennium took place at the beginning of 1001.

2 BC 1 BC 1 AD 2 3 4 5 ... 998 999 1000 1001 1002 1003 ... 1998 1999 2000 2001 2002 2003 ... 2998 2999 3000 3001 3002 3003 ...
First one thousand years (millennium) Second millennium Third millennium Fourth millennium

Arthur C. Clarke gave this analogy (from a statement received by Reuters): "If the scale on your grocer's weighing machine began at 1 instead of 0, would you be happy when he claimed he'd sold you 10 kg of tea?" This statement illustrates the common confusion about the calendar.

If one counts from the beginning of AD 1 to the ending of AD 1000, one would have counted 1000 years. The next 1000 years (millennium) would begin on the first day of 1001. So the calendar has not 'cheated' anyone out of a year. Clarke made reference to this viewpoint in his book 3001: The Final Odyssey referring to the Millennium Celebrations on December 31, 2000. In other words, the argument is based on the fact that the last year of the first two thousand years in the Gregorian calendar was 2000, not 1999.

Viewpoint 2: x000–x999

The "year 2000" has also been a popular phrase referring to an often utopian future, or a year when stories in such a future were set, adding to its cultural significance. There was also media and public interest in the Y2K bug. People liked to compared their odometer as a reason to celebrate the new millennium which goes from 1999 to 2000. Thus, the populist argument was that the new millennium should begin when the zeroes "rolled over" to 2000, i.e., the day after December 31, 1999. People[3] felt that the change of the hundreds digit in the year number, and the zeros rolling over, created a sense that a new century had begun.

This is similar to the common demarcation of decades by their most significant digits, e.g., naming the period 1980 to 1989 as the 1980s or "the eighties". Similarly, it would be valid to celebrate the year 2000 as a cultural event in its own right, and name the period 2000 to 2999 would be "the 2000s". In other words, the time period between 1 and 999 (999 years only) would be called the "0s" and the period between 1000 and 1999 would be the "1000s".

Illustration of years with a 99–00 demarcation using 0 (ISO 8601 and astronomical numbering system)
 0   1   2   3   4   5   ...   998   999  1000 1001 1002 ... 1998 1999 2000 2001 2002 ... 2998 2999 3000 3001 3002
First millennium (1000 years) Second millennium Third millennium fourth millennium
Illustration of years with a 99–00 demarcation (starting AD 1)
1 BC 1 AD  2   3   4   5   ...  998 999 1000 1001 1002 ... 1998 1999 2000 2001 2002 ... 2998 2999 3000 3001 3002
First millennium Second millennium Third millennium Fourth millennium

Popular approach

The majority[4] popular approach was to treat the end of 1999 as the end of a millennium and to hold millennium celebrations at midnight between December 31, 1999 and January 1, 2000, as per viewpoint 2. The cultural and psychological significance of the events listed above combined to cause celebrations to be observed one year earlier than the formal Gregorian date.[5] This does not establish that insistence on the formal Gregorian date is "incorrect", though some view it as pedantic.

Some event organisers hedged their bets by calling their 1999 celebrations things like "Click" referring to the odometer-like rolling over of the nines to zeros. A second approach was to adopt two different views on the millennium problem and celebrate the new millennium twice.

Popular culture

  • Stephen Jay Gould noted in his essay Dousing Diminutive Dennis' Debate (or DDDD = 2000) (Dinosaur in a Haystack) that celebrations and media announcements marked the turn into the twentieth century along the boundary of 1900 and 1901, citing, among other examples, the New York Times' headline "Twentieth Century's Triumphant Entry" on January 1, 1901. Gould also included comments on adjustments to the calendar, such as those by Dionysius Exiguus (the eponymous "Diminutive Dennis"), the timing of celebrations over different transitional periods, and the "high" versus "pop" culture interpretation of the transition. Further of his essays on this topic are collected in Questioning the Millennium: A Rationalist's Guide to a Precisely Arbitrary Countdown.
  • Douglas Adams highlighted the sentiment that those in favour of a 2001 celebration were pedantic spoilsports in his short web-article Significant Events of the Millennium. This sentiment was also demonstrated when, in 1997, Australian Prime Minister John Howard made a point in favour of the 2001 celebration and was named "the party pooper of the century" by local newspapers.
  • In an episode of the American television series, Seinfeld, titled "The Millennium" and airing in May 1997, Jerry Seinfeld states, "Since there was no year zero, the millennium doesn't begin until the year two-thousand and one." Jerry then says that Newman's hotel reservation in Times Square on NYE 2000 will be a year late, because the world was preparing to celebrate the millennium on NYE 1999.[6]
  • The action of the book The Headless Bust: A Melancholy Meditation on the False Millennium, by Edward Gorey, takes place on December 31, 1999, and it refers to the next coming year as the start of the new millennium, despite the fact that the title of the book calls it the "False Millennium."
  • During 1999, the term millennium (referring to the year 2000) became a heavily used buzzword in German media, so that it was chosen as German Word of the Year by the Gesellschaft für deutsche Sprache.[7]
  • In a 1999 episode of the American television series The X-Files titled "Millennium", Dana Scully notes that the new millennium does not actually start until 2001, to which Fox Mulder replies, "Nobody likes a math geek, Scully."
  • In 2000, a special 'Millennium Pie' was baked in the world-famous 'pie village' of Denby Dale, home to the Denby Dale Pie Company. The creation fed over 22,000 people, with the first slice cut by cricket umpire Dickie Bird.

See also


  1. ^ "millennium", Oxford Dictionaries (Oxford University Press, 2016).
  2. ^ Gould, Stephen Jay, Questioning the Millennium (New York: Harmony Books, 1997), part 2.
  3. ^ "When Does the New Millennium Begin?" January 1, 1999.
  4. ^ Associated Press, "Y2K It Wasn't, but It Was a Party", Los Angeles Times, January 1, 2001.
  5. ^ "Y2K". Associated Press. Articles.latimes.com. 2001-01-01. Retrieved 2014-08-14. 
  6. ^ "The Millennium". Seinfeld Scripts. 1997-05-01. Retrieved 2014-08-14. 
  7. ^ Von Christoph Gunkel (2011-10-31). "Deutsche Sprachpreise - SPIEGEL ONLINE". Einestages.spiegel.de. Retrieved 2014-08-14.