The Quaternary Ice Age is a geological period that began about 2.58 million years ago and continues to the present day. It is characterized by repeated glacial cycles, where large ice sheets expanded and retreated across parts of the Earth, particularly in the northern hemisphere. This period is divided into two epochs: the Pleistocene, marked by extensive glaciation, and the Holocene, which is the current warm interglacial period. During the Quaternary Ice Age, significant changes occurred in the Earth's climate, ecosystems, and species. Many large mammals, such as the woolly mammoth and the saber-toothed cat, thrived during the Pleistocene but went extinct as the climate warmed. The Quaternary Ice Age has greatly influenced the development of human civilizations and the distribution of flora and fauna across the planet.