What is the first year of the twenty-first century?

A millennium is by definition "a period of 1000 years." The 3rd Millennium starts January 1st, year 2001 NOT year 2000 as many people believe, when using the Gregorian calendar. The reason why the 3rd Millennium / 21st Century starts in 2001 is because there was no year 0 (or AD 0, 0 BC). The year before 1 A.D. is defined as year 1 B.C., so year 0 was skipped. Because one Millennium is 1000 years, the first Millennium ends with year 1000. The next (2nd) Millennium starts 1000 years after the first, that is in year 1+1000 = 1001. And the 3rd one starts 1000 years later than the 2nd: 1001+1000 = 2001. The same procedure could be followed for centuries.

More Info: www.timeanddate.com

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28 Comments

Pierre Poirier

To all the wrong answer people : our calendar did not begin with year 0. It began with year one . Therefore, the first Century was from year one to year 100. And so on... so the 21 st indeed began in 2001

Howard Groopman

Yes, many people thought Y2K (1-1-2000) was the first year of the 21st century, but it was the last year of the 20th. Millennia end in 00.

Player

Vance Duncan, America (and maybe other countries) have the ground level floor of a building as 1. Which has about as much to do with the first year in a century as programming.

Chris Brown

Pierre Poirier, Precisely. Thank you. I was about to comment similarly.

earlepg

Apparentlly there was no year zero, so I must accept 2001 as the beginning the twenty-first century. This has been debated at least since 1999. Still no concensus?

Robert Oldenburg

One question, what was the view in previous centuries. At the time the people in 1900 considered that year the first year of the 20th century. As far as I know the same was true in 1800 and 1700 etc.

Vance Duncan

Gregory obviously knew nothing of C (and it’s derivatives) programming. Every self-respecting programmer knows lists start with index 0.

Louella Wilson

If you want to simplify the argument and count on your fingers, think of the question being decades. The first decade is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. Thus 11 starts the second decade which runs to 20. 21 starts the third decade etc. Curiously that was once considered to be coming of age. I believe that is still the legal drinking age in many places.

Mark G. Feeney

John W Shreve, Decades are defined differently. He hit .300 in the '30s, '40s, '50s, and '60s

Ray Anderson

I'm sure that this argument will go on till the next century and beyond.

Comniní Tsinari

Alan Waites, celebrations make money.

Richard D. Boyle

Brief but excellent narrative answer and options.

Richard D. Boyle

Stephen Knapp, Your baby example makes perfect sense but it doesn’t apply to the turning of the centuries for the reason perfectly explained by the author. The year zero was skipped and we have lived with this technical anomaly ever since...by just ignoring it.

John W Shreve

That means Ted Williams did not hit .300 in four different decades.

Ken Jackson

Kim Hernandez, it wasn't - it was the end of the 20th century. A century is 100 years, not 99 years. There was no year 0, so the first century finished at the end of the year 100, the second finished at the end of the year 200 and so on.