How do we classify the history of the Earth?

Like the history of human civilization, the history of the Earth too is divided into periods. However, these periods cover  not just a few centuries, but millions of years.

Broadly, we differentiate between the time preceding the period 550million years ago and the time after that, during which life developed very quickly on the Earth. Researchers have gathered a lot of data regarding the different periods of the Earth's history by studying fossils. Thus, we came to know at  what time fishes 

and birds appeared on the Earth, Why plants and animals lived in the sea for so long, and what the different types of 🦕 🦕 🦕 🦕 🦕 ate.