The Quaternary Period is the most recent geological period, beginning about 2.6 million years ago and continuing to the present day. It is characterized by significant climate changes, including repeated glacial and interglacial cycles, which have shaped the Earth's landscape and ecosystems. This period is divided into two epochs: the Pleistocene, known for its ice ages, and the Holocene, which is the current warm period. During the Quaternary, many species, including large mammals like the woolly mammoth and the saber-toothed cat, went extinct, while others adapted to changing environments. The period also saw the rise of humans, who developed tools and agriculture, significantly impacting the planet's ecosystems and leading to the development of civilizations.