The Precambrian era covers the creation of Earth up until the emergence of multi-celled life forms. The Precambrian accounts for roughly seven-eighths of Earth's history or approximately 4 billion years. The conclusion of this period came 570 million years ago, when the Earth's crust formed and complex life first took form in the seas.
The Precambrian is not a true geologic era, but instead a period of time, containing three distinct eons: the Hadean, which was 4.5 to 4 million years ago, the Archean, which was 4 billion to 2.5 billion years ago, and the Proterozoic, which was 2.5 billion to 541 million years ago.
These periods contain the evidence to elucidate the formation of Earth's landmasses, oceans and ultimately the creation of complex life. The Hadean period features the formation of the Milky Way and the first stages of Earth. The Archean period features the cooling of the Earth, the formation of water in the atmosphere and the creation of the first life forms. The Proterozoic period features the creation of oxygen in the Earth's atmosphere and the further evolution of life.
The Precambrian time period was a brutal time in Earth's history. Beginning with the formation of the planet from gas and space dust and lasting to the first formation of life with single cell algae, this time period ultimately shaped the planet as it is known today.