This book introduces questions of astrobiology and exoecology and provides a comprehensive overview of the latest research findings, past setbacks, and future missions of leading space agencies. From astrophysical, geo- and bioecological perspectives, it presents exotic worlds and their inhabitants to the reader, expanding our earthly concepts to an astronomical scale and illuminating the phenomenon of life in a new starlight. Will we find extraterrestrial life forms in this century? And what biosignatures should we search for on distant celestial bodies to detect extraterrestrial ecosystems?.