The interpretation of genomes will constitute the most exciting and most significant science of the century. By rapidly advancing our understanding of life, how it arose, and how it continues to change, we will acquire the tools that will allow us to better understand and improve our existence. Understanding has begun with relatively simple forms of life - unicellular organisms. While the central mechanisms of life are shared by both these organisms and the most complex animals and plants, they also contain a remarkable diversity. They have an immense amount to teach us about life itself.