Century

A century is a period of 100 years. Centuries are numbered ordinally in English and many other languages. The word century comes from the Latin centum, meaning one hundred. Century is sometimes abbreviated as c.[1]

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).

According to the strict construction of 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).[2] This is the definition generally used on Wikipedia.

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.[3]

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