# the 21st century

CEFR A1 · Compound

Source: https://englishreference.com/word/the-21st-century
Updated: 2026-04-24

## Definition

The period of time from the year 2001 to 2100. We are living in the 21st century right now.

For teachers: The hundred-year period from 1 January 2001 to 31 December 2100 in the Gregorian calendar.

## Examples

- We live in the 21st century.
- Many challenges of the 21st century, like climate change, require global cooperation.
- Future historians will likely characterize the early 21st century by its rapid technological acceleration and profound social transformations.

## Pitfalls

- Not "Life in 21st century is very different." but "Life in the 21st century is very different." — The definite article 'the' is required before an ordinal number like '21st' when it names a specific century.

## Usage notes

- Used to refer to the current hundred-year period, often to discuss modern trends or technology.
- Teaching tip: Address the common confusion that the 21st century began on January 1, 2001, not in the year 2000, as there was no 'year zero'.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.