century

The smallest unit in a Roman legion, under the command of a centurion. Probably consisting originally of 100, under the Empire there were 80 soldiers in a century.

A century (From the Latin cent, one hundred) is one hundred consecutive years. Thus, the first century of a time frame is "The First Century" and not "Century 0". 2000) as the first or last year of a century. This confusion is documented for every centennial year from 1500 onward, and almost certainly arises from the introduction of Hindu-Arabic numerals and the concept of zero to Western Europe in the twelfth century. the Islamic calendar as the year of the Hejira, so it is also latinized as Anno Hejira.

In the Gregorian calendar, the calendar that is currently used for most purposes nearly everywhere in the world, the first year is that of the traditionally accepted year of Jesus' birth. Accordingly, the first century includes the years 1-100 anno Domini, the first millennium (or period of ten centuries) is the years 1-1000 anno Domini, and so on.

More modern systems of dating (such as that of astronomical year numbering, used by astronomers) begin with a year zero. In these cardinal dating systems, it is perfectly logical to use 0 to 99 as the first century, and to regard 2000 as the first year of the twenty-first century.