What is quatiary?

"Quaternary" typically refers to the Quaternary period in geological time, which is the most recent geological time period, spanning from about 2.6 million years ago to the present. It is characterized by significant climatic changes, the development of human civilizations, and the dominance of mammals and birds. The Quaternary is subdivided into two epochs: the Pleistocene, known for its ice ages, and the Holocene, which encompasses the current interglacial period. Additionally, "quaternary" can refer to the fourth level or stage in various contexts, such as in chemistry or education.