The life is a concept that is challenging to define, but it is the property that distinguishes matter with biological processes and self-sustainability from matter without them. Evidence suggests that life has existed on Earth for at least 3,770-4,280 million years, with estimates indicating it emerged around 4,350 million years ago. Throughout this time, most major lineages of living organisms have gone extinct, contributing to the homogenization of the biological characteristics of currently known organisms. Nowadays, all diversity can be grouped into three major domains: Archaea, Bacteria, and Eukaryota. The Eukaryota domain, the only one containing macroscopic organisms such as animals and plants, originated from a lineage of Archaea that experienced an endosymbiosis with a species of Bacteria, forming combined genomes that gifted these organisms with new metabolic capabilities.

Below is a phylogenetic reconstruction of the three major lineages that comprise life: