A decade () is a period of ten

year A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the h ...

s. Decades may describe any ten-year period, such as those of a person's life, or refer to specific groupings of

calendar year Generally speaking, a calendar year begins on the New Year's Day of the given calendar system and ends on the day before the following New Year's Day, and thus consists of a whole number of days. A year can also be measured by starting on any ...

Usage

Any period of ten years is a "decade". For example, the statement that "during his last decade, Mozart explored chromatic harmony to a degree rare at the time" merely refers to the last ten years of

Wolfgang Amadeus Mozart Wolfgang Amadeus Mozart (27 January 17565 December 1791), baptised as Joannes Chrysostomus Wolfgangus Theophilus Mozart, was a prolific and influential composer of the Classical period. Despite his short life, his rapid pace of composition r ...

's life without regard to which calendar years are encompassed. Also, 'the first decade' of a person's life begins on the day of their birth and ends at the end of their 10th year of life when they have their 10th

birthday A birthday is the anniversary of the birth of a person, or figuratively of an institution. Birthdays of people are celebrated in numerous cultures, often with birthday gifts, birthday cards, a birthday party, or a rite of passage. Many re ...

; the second decade of life starts with their 11th year of life (during which one is typically still referred to as being "10") and ends at the end of their 20th year of life, on their 20th birthday; similarly, the third decade of life, when one is in one's twenties or 20s, starts with the 21st year of life, and so on, with subsequent decades of life similarly described by referencing the tens digit of one's age.

0-to-9 decade

The most widely used method for denominating decades is to group years based on their shared tens digit, from a year ending in a 0 to a year ending in a 9 for example, the period from 1960 to 1969 is the 1960s, and the period from 1970 to 1979 is the 1970s. Sometimes, only the tens part is mentioned (''60s'' or ''sixties'', and ''70s'' or ''seventies''), although this may leave it ambiguous as to which

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. A centennial or ...

is meant. However, this method of grouping decades cannot be applied to the decade immediately preceding AD10, because there was no year 0. Particularly in the 20th century, ''0-to-9'' decades came to be referred to with associated nicknames, such as the "

Swinging Sixties The Swinging Sixties was a youth-driven cultural revolution that took place in the United Kingdom during the mid-to-late 1960s, emphasising modernity and fun-loving hedonism, with Swinging London as its centre. It saw a flourishing in art, mu ...

" (

1960s File:1960s montage.png, Clockwise from top left: U.S. soldiers during the Vietnam War; the Beatles led the British Invasion of the U.S. music market; a half-a-million people participate in the 1969 Woodstock Festival; Neil Armstrong and Buzz ...

), the "Warring Forties" (

1940s File:1940s decade montage.png, Above title bar: events during World War II (1939–1945): From left to right: Troops in an LCVP landing craft approaching Omaha Beach on D-Day; Adolf Hitler visits Paris, soon after the Battle of France; The Ho ...

) and the "

Roaring Twenties The Roaring Twenties, sometimes stylized as Roaring '20s, refers to the 1920s decade in music and fashion, as it happened in Western society and Western culture. It was a period of economic prosperity with a distinctive cultural edge in th ...

" (

1920s File:1920s decade montage.png, From left, clockwise: Third Tipperary Brigade Flying Column No. 2 under Seán Hogan during the Irish War of Independence; Prohibition agents destroying barrels of alcohol in accordance to the 18th amendment, which ...

). This practice is occasionally also applied to decades of earlier centuries; for example, referencing the

1890s The 1890s (pronounced "eighteen-nineties") was a decade of the Gregorian calendar that began on January 1, 1890, and ended on December 31, 1899. In the United States, the 1890s were marked by a severe economic depression sparked by the Panic of ...

as the "

Gay Nineties The Gay Nineties is an American nostalgic term and a periodization of the history of the United States referring to the decade of the 1890s. It is known in the United Kingdom as the Naughty Nineties, and refers there to the decade of supposedly ...

" or "Naughty Nineties".

1-to-0 decade

A rarer approach groups years from the beginning of the AD calendar era to produce successive decades from a year ending in a 1 to a year ending in a 0, with the years 1–10 described as "the 1st decade", years 11–20 "the 2nd decade", and so on; later decades are more usually described as 'the st, nd, rd, or th decade of the st, nd, rd, or th century' (using the strict interpretation of 'century'). For example, "the second decad of the 12th. Cent." ''( sic)''; "The last decade of that century"; "1st decade of the 16th century"; "third decade of the 16th century"; "the first decade of the 18th century". This decade grouping may also be identified explicitly; for example, "1961–1970"; "2001–2010"; "2021–2030". The BC calendar era ended with the year 1BC and the AD calendar era began the following year, AD1. There was no year 0.

Public usage of the two methods

YouGov YouGov is a British international Internet-based market research and data analytics firm, headquartered in the UK, with operations in Europe, North America, the Middle East and Asia-Pacific. In 2007, it acquired US company Polimetrix, and sinc ...

poll was conducted on December 2, 2019, asking 13,582 adults in the United States, "When do you think the next decade will begin and end?" Results showed that 64% answered that "the next decade" would begin on January 1, 2020, and end on December 31, 2029 (''0-to-9'' method); 17% answered that "the next decade" would begin on January 1, 2021, and end on December 31, 2030 (''1-to-0'' method); 19% replied that they did not know.

References

Notes

External links

Definition
from Etymology Online {{Time measurement and standards Units of time Periodic phenomena