21st century

In calendars based on the Christian Era or Common Era, such as the Gregorian calendar, the 21st century is the current century, as of this writing. By some interpretations, it lasts from 2001 to 2100, and the 3rd millennium lasts from 2001 to 3000. This is based on the argument that there was no Year Zero, so the first century began in year 1 http://www.astronomyboy.com/millennium/. However, common usage often regards the 21st century as lasting from 2000 to 2099. In 2000 the ISO implicitly backed this common usage by creating a calendar that incorporates a Year Zero (see 20th century). Decades are almost always considered as starting with the "0" year and named accordingly ("2010s", etc.), so the first decade of a century could overlap back into the preceding one.

External links

• Long Bets Foundation to improve long-term thinking
• Long Now Long-term cultural institution