The Precambrian Era is the very first part of the Earth's history. Its name refers to this era preceding the one that came after it - the Cambrian.
The Precambrian Era began 4.6 billion years ago and ended 541 million years ago, thus encompassing 90% of the planet's history.
Since it happened long ago, there isn't that much evidence of that big period of time. Bacteria fossils that are more than 3 billion years old were found. More complex organisms like algae appeared during Proterozoic eon (the latest part of the Precambrian era).
