A decade is ten years. It is a long time. You can use it for your life. You can use it for years. It helps us count time. We can look back at old times. How many years have you lived?
A decade is ten years. It is a long time. You can use it to count your life. Your first ten years is your first decade. Then your second decade begins. People also group years by their numbers. They might call them the sixties. This means years like 1960 to 1969. Some people group them differently. They might count from year one to ten. There was no year zero in the old calendar. This makes counting a bit tricky. Decades help us talk about time.
A decade is a period of ten years. You might also hear it called a decennium. People use this word to talk about time in different ways.
You can use it to describe a person's life. Your first decade starts at birth. It ends on your tenth birthday. Your second decade starts when you turn eleven. This continues as you grow older.
Many people group years by their ending numbers. This is the 0-to-9 method. For example, the 1960s go from 1960 to 1969. Some decades even have nicknames. People called the 1920s the "Roaring Twenties." The 1960s were called the "Swinging Sixties."
Other people use a 1-to-0 method. This groups years from one to ten. For example, one group might use 2021 to 2030. This way is less common.
In a 2019 study, many adults were asked about the next decade. Most people thought it would run from 2020 to 2029. However, some people thought it would run from 2021 to 2030. This shows that people use different ways to group time.
A decade is a period of ten years. You might also hear people call it a decennium. This word helps us talk about chunks of time. We can use it for calendar years. We can also use it to describe a person's life. For example, Mozart explored new music in his last decade. This means the last ten years of his life.
Decades of a life follow a steady pattern. Your first decade starts on the day you are born. It ends on your tenth birthday. Your second decade starts during your eleventh year. It ends when you turn twenty. This pattern continues as you grow older. We use the tens digit of your age to name them. Your third decade includes your twenties.
There are two main ways to group years. The most common way is the 0-to-9 method. This groups years by their shared tens digit. For example, the 1960s run from 1960 to 1969. People often use nicknames for these groups. The 1920s were called the "Roaring Twenties." The 1940s were the "Warring Forties." The 1960s were the "Swinging Sixties." This grouping became common in the late 19th century.
A rarer way is the 1-to-0 method. This groups years from one to ten. One group might be 2021 to 2030. This is called the 1st decade of the 21st century. This method cannot work for the very first decades. There was no year zero in the AD calendar. The BC era ended with 1BC. The AD era began with AD1.
People often disagree on when a decade begins. A YouGov poll asked adults in the United States this question. The poll happened on December 2, 2019. It asked 13,582 adults about the next decade. About 64% used the 0-to-9 method. They thought it would run from 2020 to 2029. About 17% used the 1-to-0 method. They chose the years 2021 to 2030. The rest of the people did not know.
A decade is a specific unit of time lasting ten years. You may also encounter the term decennium to describe this same period. Decades serve as helpful tools for organizing history and human experience. We use them to describe large chunks of calendar years. We also use them to measure segments of a person's life. For example, we might say a composer explored new musical styles during his last decade. This refers to the final ten years of that person's existence.
Decades of a human life follow a very specific mathematical pattern. A person's first decade begins on the day of their birth. It concludes when they reach their tenth birthday. The second decade of life starts with the eleventh year of life. This period ends when the person reaches their twentieth birthday. The third decade begins with the twenty-first year of life. This is why people in their twenties are often said to be in their third decade. We continue this pattern by referencing the tens digit of a person's age.
There are two primary methods used to group calendar years into decades. The most widely used approach is the 0-to-9 method. This system groups years based on a shared tens digit. For example, the years from 1960 to 1969 are called the 1960s. People often shorten these names to the "sixties" or "seventies." This method became a common way to talk about time in the late 19th century. However, this naming can sometimes be ambiguous regarding which century is being discussed.
During the 20th century, certain decades gained unique cultural nicknames. These names often reflect the atmosphere of that specific time. The 1920s were famously known as the "Roaring Twenties." The 1940s were sometimes called the "Warring Forties." The 1960s earned the nickname "the Swinging Sixties." People have even applied nicknames to earlier centuries. For instance, the 1890s were sometimes called the "Gay Nineties" or the "Naughty Nineties."
A second, rarer approach is known as the 1-to-0 method. This method groups years starting from the beginning of a calendar era. It produces successive decades from a year ending in 1 to a year ending in 0. For example, the years 1 through 10 are called the 1st decade. The years 11 through 20 would be the 2nd decade. In later history, people describe these using the ordinal number of the century. An example is the "first decade of the 18th century." You might also see these periods written explicitly as 2021–2030.
The 1-to-0 method has a unique limitation regarding the start of our current calendar. The Anno Domini (AD) calendar system does not include a year zero. The BC calendar era ended with the year 1BC. The AD era began immediately after with the year AD1. Because there is no year zero, the 0-to-9 method cannot be applied to the decades immediately preceding AD10. This creates a distinct break in how we group the very earliest years of the AD era.
Because there are two different methods, people often disagree on when a decade starts. A YouGov poll conducted on December 2, 2019, examined this exact confusion. Researchers asked 13,582 adults in the United States when the next decade would begin and end. The results showed that 64% of participants used the 0-to-9 method. They believed the next decade would run from January 1, 2020, to December 31, 2029. Meanwhile, 17% of respondents used the 1-to-0 method. They believed the decade would run from 2021 to 2030. The remaining 19% of people stated they did not know.
Where will your curiosity go next?
More to explore
✨ What else?
Related topics you might enjoy
What is Nepedia?
A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.