What is an Ice Age?
An Ice Age is a period of time when large areas of the Earth are covered in ice and snow. These large ice masses are called glaciers.
The term "Ice Age" is used in two different contexts. The first is to refer to long and generally cold periods during Earth's history (tens to hundreds of million years) in which glaciers would advance and retreat. The second is to refer to shorter periods of time in Earth's history (tens of thousands of years) during which glaciers were near their maximum extent. These shorter intervals are also known as "glaciations."
The term is also used quite commonly to refer to the most recent glaciation in Earth's history which began about 1.8 million years ago. When the term is used in this sense, the first letter of both words are capitalized. (ie. "Ice Age").