One century holds one hundred years
A century is a period of one hundred years. When we say “the first century”, we mean the first numbered group of one hundred years.
Imagine a box that holds 100 year cards. Put cards 1, 2, 3 and so on into it. Card 100 fills the last space. Card 101 must go in the next box.
The second box holds years 101 to 200. The third holds 201 to 300. Each box is one century.
Why 1900 belongs in the nineteenth box
Following the same pattern, the nineteenth box starts at 1801 and finishes at 1900. That is the 19th century.
The twentieth box starts with the very next card: 1901. It finishes at 2000.
It feels odd because 1900 and 1901 both start with “19”. But one is the last card in a full box, and the other is the first card in a new one.
Three boxes you will often meet
| Century | First year | Last year |
|---|---|---|
| 19th century | 1801 | 1900 |
| 20th century | 1901 | 2000 |
| 21st century | 2001 | 2100 |
So the 21st century began in 2001. The year 2000 was the final year of the twentieth box.
Try a date on the edge
The 16th century runs from 1501 to 1600. Where should the next year, 1601, go?
Open the next box
Into the 17th century. The old box finished with 1600, so 1601 starts a new one.
You may see CE after a year. It means “Common Era”; AD is another label used for the same year numbering. In this numbering, the first century begins with year 1, not year 0.
This article uses those year numbers. Dates marked BCE or BC describe earlier years and need a separate explanation.