The term "Phanerozoic" refers to the current geological eon, which began around 541 million years ago and continues to the present. It is characterized by the abundance of fossil evidence and the emergence of complex life forms, including plants and animals. The Phanerozoic is divided into three major eras: Paleozoic, Mesozoic, and Cenozoic. During the Phanerozoic, significant events such as the Cambrian Explosion, which saw a rapid increase in biodiversity, and the extinction of the dinosaurs at the end of the Cretaceous period have shaped the planet's biological history. This eon has been crucial for understanding the evolution of life on Earth.