Century

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For other uses, see Century (disambiguation).

"Centennial" redirects here. For other uses, see Centennial (disambiguation).

"Centenary" redirects here. For other uses, see Centenary (disambiguation).

A century (From the Latin cent, one hundred) is one hundred consecutive years. Centuries are numbered ordinally (e.g. "The Seventh Century AD").

1 Start and End in the Gregorian Calendar
- 1.1 End of the 20th century
- 1.2 1st Century AD and BC
2 Dating Systems before the Century
3 Centuries in Astronomical Year Numbering
4 References
5 See also

Start and End in the Gregorian Calendar

According to the Gregorian calendar, the 1st century AD started on January 1, 1 and ended on December 31, 100. The 2nd century started at year 101, the third at 201, etc. The n-th century will start on the year 100×n - 99. A century will only include one year, the centennial year, that starts with the century's number (e.g. 1900 is in the 19th century).

End of the 20th century

It is commonly-held misconception that the 20th century ended on December 31, 1999. The 20th century actually ended on December 31, 2000, its centennial year.

1st Century AD and BC

There is no "zeroth century" in between the 1st century BC and the 1st century AD. The first century BC includes the years 100 BC to 1 BC. Other centuries BC follow the same pattern.

Dating Systems before the Century

The oldest dating systems were based on the reigns of monarchs, (e.g. the fifteenth year of King George). Similarly, other systems arose dating from the founding of a dynasty, city or religion. For example, Ab urbe condita counts the Year 1 as the founding of Rome, Anno Domini as the first full year of Jesus Christ's life and the Islamic calendar counts in the year of the Hijra. The Gregorian calendar adopted Anno Domini as the basis for its numbering system.

Centuries in Astronomical Year Numbering

Astronomical year numbering, used by astronomers) includes a year zero. Consequently, the first century in these calendars may designate the years 0 to 99 as the first century. and to regard 2000 as the first year of the twenty-first century, the year 0 corresponding then to Georgian year 1 BC.

References

"The Battle of the Centuries", Ruth Freitag, U.S. Government Printing Office. Available from the Superintendent of Documents, PO Box 371954, Pittsburgh, PA 15250- 7954. Cite stock no. 030-001-00153-9.

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