Century

"Centuries" and "Centenary" redirect here. For other uses, see Century (disambiguation), Centuries (disambiguation), and Centenary (disambiguation).

A century (from the Latin centum, meaning one hundred; abbreviated c.) is a period of 100 years. Centuries are numbered ordinally in English and many other languages.

A centenary is a hundredth anniversary, or a celebration of this, typically the remembrance of an event which took place a hundred years earlier.

Start and end in the Gregorian calendar

Although a century can mean any arbitrary period of 100 years, there are two viewpoints on the nature of standard centuries. One is based on strict construction, while the other is based on popular perspective (general usage).

As some authorities, such as the United States Naval Observatory, interpret the Gregorian calendar, the 1st century AD began with 1 AD and ended with 100 AD, with the same pattern continuing onward. In this model, the n-th century started/will start on the year (100 × n) − 99 and ends in 100 × n. Because of this, a century will only include one year, the centennial year, that starts with the century's number (e.g. 1900 was the last year of the 19th century).

In general usage, centuries are aligned with decades by grouping years based on their shared digits. In this model, the 'n' -th century started/will start on the year (100 x n) - 100 and ends in (100 x n) - 1. For example, the 20th century is generally regarded as from 1900 to 1999, inclusive. This is sometimes known as the odometer effect. The astronomical year numbering and ISO 8601 systems both contain a year zero, so the first century begins with the year zero, rather than the year one.

Viewpoint 1: Strict usage

2 BC	1 BC	1	2	3	4	5	...	96	97	98	99	100	101	102	103	...	198	199	200	...	1901	1902	...	1998	1999	2000	2001	2002	2003	...	2098	2099	2100	2101	2102	2103	...	2198	2199	2200
		1st century											2nd century							...	20th century						21st century							22nd century

Viewpoint 2: General usage

2 BC	1 BC	1	2	3	4	5	...	96	97	98	99	100	101	102	103	...	198	199	...	1900	1901	1902	...	1998	1999	2000	2001	2002	2003	...	2098	2099	2100	2101	2102	2103	...	2198	2199
		1st century										2nd century							...	20th century						21st century							22nd century

Alternative naming systems

Informally, years may be referred to in groups based on the hundreds part of the year. In this system, the years 1900–1999 are referred to as the nineteen hundreds (1900s). Aside from English usage, this system is used in Swedish, Danish, Norwegian, Icelandic and Finnish. The Swedish nittonhundratalet (or 1900-talet), Danish nittenhundredetallet (or 1900-tallet), Norwegian nittenhundretallet (or 1900-tallet) and Finnish tuhatyhdeksänsataaluku (or 1900-luku) refer unambiguously to the years 1900–1999.

Similar dating units in other calendar systems

While the century has been commonly used in the West, other cultures and calendars have utilized differently sized groups of years in a similar manner. The Hindu calendar, in particular, summarizes its years into groups of 60, while the Aztec calendar considers groups of 52.

See also

• Age of Discovery
• Ancient history
• Before Christ
• Common Era
• Decade
• List of centuries
• Lustrum
• Middle Ages
• Millennium
• Modern era
• Saeculum
• Year

Bibliography

• 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.