The Ice Age - Glacial and Interglacial Stages

The last 2.6 million years or so is called the Quaternary period. 
During that time, glacial stages were times of extreme cooling of the Earth's climate, where ice sheets and other types of glacier expanded to cover large areas of land. 
Between glacial stages there were warmer interglacial stages, and we are now living during such a time.
This useful chart shows the UK timeline for the later part of times.... 'ka' refers to 1000s of years. In other places, other names are used.
When people talk about the 'Ice Age', they are often referring to the most recent glacial period, which peaked about 21,000 years ago, and ended about 11,000 years ago.

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