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

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, P.O. Box 371954, Pittsburgh, PA 15250- 7954. Cite stock no. 030-001-00153-9.

See also

• List of centuries

af:Eeue ar:??? (???) ast:Sieglu zh-min-nan:Sč-kí be:????????? bs:Vijek br:Kantved bg:??? ca:Segle cv:???? cs:Století da:Ĺrhundrede de:Jahrhundert et:Sajandid el:?????? es:Siglo eo:Jarcento eu:Mende fa:??? fr:Sičcle fy:Ieu ga:Aois gl:Século ko:?? hr:Stolje?e id:Abad is:Öld it:Secolo he:??? (???) jv:Abad kn:????? ka:??????? sw:Karne ht:Syčk ku:Sedsal la:Saeculum lv:Gadsimts lt:Am?ius ln:Bonkámá hu:Évszázad ms:Abad mn:???? nl:Eeuw ja:?? no:Ĺrhundre nrm:Syiclle pl:Wiek pt:Século ro:Secol rmy:Shelbersh ru:??? scn:Sčculu simple:Century sk:Storo?ie sl:Stoletje sr:??? sh:Vijek su:Abad fi:Vuosisata sv:Sekel tl:Daang Taon ta:?????????? th:?????? vi:Th? k? tg:??? tr:Yüzy?l uk:???????? ur:???? ???? fiu-vro:Aastagasada yo:??rúndún zh-yue:?? zh:??