Historians often group events by hundred-year spans. A century is a period of one hundred years, conventionally counted from year 1 of an era or from any chosen starting point. The twentieth century, for example, runs from 1901 to 2000 in strict usage, though popular speech sometimes treats 1900–1999 as the block.

Centuries serve as convenient containers for summarizing trends—industrialization, world wars, or decolonization—even when the underlying processes began earlier or continued later. Naming a century can also carry cultural weight, as with the “long nineteenth century” that some scholars extend from 1789 to 1914.

The unit itself is arbitrary; nature and society do not reset every hundred years. Yet the century remains a practical shorthand in teaching, publishing, and public discussion. It helps readers orient themselves within the larger flow of historical time.

• Period of one hundred years
• Used to organize historical narrative
• Boundaries can be strict or flexible
• Convenient but ultimately conventional unit