A decade is a period of 10 years. The term decade comes from the Greek dekas (δεκάς) which means a group of ten. We currently live in the second decade of the 21st Century or 2020s (twenty-twenties).  

The 2020s have begun from 2020 and will continue up to 2029. 

When Does A Decade Begin and End

Farmer's Almanac and The US Naval Observatory have established that a decade begins with the year ending in 1 and ends with the year ending with zero. For example, the current decade started with 2021 and will end with 2030. The universally followed Gregorian calendar also abides by this system.

However, some people follow another system where a decade starts with a year ending with zero and ends with a year ending with 9 (such as 2020 to 2029). Most people follow this system.

Thus, there is no universal rule as to when a decade begins or ends. It mostly depends on one's preference. 

How to Calculate Which Decade a Year Belongs To

The formula for calculating the decade a year belongs to is quite simple.

Simply replace the last digit of the year with zero and you get the decade. For example, for the year 2024, replace 4 with 0 and you get 2020s. 

Another example is 1990. Here, zero is already the last digit so it simply belongs to the 1990s decade. 

Please Note: If you follow the other method where a decade begins with a year ending with 1 and ends with a year ending with zero (2021 to 2030), the method is slightly different. 

You still replace the last digit of a year with zero if it is already not so.

However, in years already ending with zero (such as 2020, 2010, etc), it will belong to the earlier decade or 10 years before. Thus, 2020 belongs to the 2010s whereas 2010 belongs to the 2000s. 

A Timeline of the Previous Decades and Their Years

21st Century

  • 2020s: 2020 to 2029
  • 2010s: 2010 to 2019
  • 2000s: 2000 to 2009

20th Century

  • 1990s (Nineties or 90s): 1990 to 1999
  • 1980s (Eighties or 80s): 1980 to 1989
  • 1970s (Seventies or 70s): 1970 to 1979
  • 1960s (Sixties or 60s): 1960 to 1969
  • 1950s (Fifties or 50s): 1950 to 1959
  • 1940s (Forties or 40s): 1940 to 1949
  • 1930s (Thirties or 30s): 1930 to 1939
  • 1920s (Twenties or 20s): 1920 to 1929
  • 1910s (Tens or 10s): 1910 to 1919
  • 1900s: 1900 to 1909

19th Century

  • 1890s: 1890 to 1899
  • 1880s: 1880 to 1889
  • 1870s: 1870 to 1879
  • 1860s: 1860 to 1869
  • 1850s: 1850 to 1859
  • 1840s: 1840 to 1849
  • 1830s: 1830 to 1839
  • 1820s: 1820 to 1829
  • 1810s: 1810 to 1819
  • 1800s: 1800 to 1809

18th Century

  • 1790s: 1790 to 1799
  • 1780s: 1780 to 1789
  • 1770s: 1770 to 1779
  • 1760s: 1760 to 1769
  • 1750s: 1750 to 1759
  • 1740s: 1740 to 1749
  • 1730s: 1730 to 1739
  • 1720s: 1720 to 1729
  • 1710s: 1710 to 1719
  • 1700s: 1700 to 1709

Relation Between Decade, Century, Biennium, Lustrum, Score, Half-Century and Millennium

Decade, Biennium, Lustrum, score, half century, century, millennium

  • 5 Bienniums make up 1 Decade
  • 2 Lustrums make up 1 Decade
  • 2 Decades make up 1 Score
  • 5 Decades make up 1 Half-century
  • 10 Decades make up 1 Century
  • 100 Decades make up 1 Millennium

Significant Events That Happened This Decade in the 2020s

Israel Hamas War

On October 7, 2023, Hamas, a political and military wing operating in Gaza, Palestine led an attack on the occasion of Shemini Atzeret. Around 1200 people were reportedly killed in the attack and many others were taken hostages.

This also led to a fierce and deadly retaliation by Israel which killed more than 32,552 Palestinians and wounded close to 75000 people. The Israel-Hamas war has been at the forefront of global news. 

ChatGPT Launch

Chatgpt opened on a phone

The most widely used AI ChatGPT was developed and launched by OpenAI on November 30, 2022. Russian-born Computer scientist Ilya Sutskever is the brain behind ChatGPT. It currently has around 180.5 million users worldwide!

Death of Queen Elizabeth II

A banner of Queen Elizabeth II

Elizabeth II, the Queen of the UK and other Commonwealth countries died due to old age on September 8, 2022. She apparently died peacefully and without pain in her sleep. Queen Elizabeth was ninety-six when she passed away.

After her death, her eldest son Charles assumed the throne.

Return of Taliban

People protesting the return of Taliban

​2020s was a significantly life-altering decade as the US and NATO troops withdrew from Afghanistan and the Taliban came back to power on August 15, 2021. This was followed by the collapse of the Afghan Government with former President Ashraf Ghani fleeing.

Many desperate citizens flocked to the airport to leave the country. 

Joe Biden Becomes the President of the United States of America

President Joe Biden talks on the phone with Katherine Tai in the Oval Office of the White House

Joe Biden became the 46th President of the United States of America on January 20, 2021. He won against former President Donald Trump in a historic election. Biden is the oldest President in the history of the US who was 78 years old when he was sworn in as the President of the US. 

2020s And 203rd Decade

The 2020s decade is actually different from the 203rd decade.

The 2020s began from 2020 to 2029 whereas the 203rd decade began from 2021 and continues up to 2030. Thus, both of them follow different systems and consequently have different names. 

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