Since the discovery in 1992 of the first exoplanet, the number of planet detections has increased exponentially and ambitious missions are already being planned for the future. The exploration of Earth and the rest of the rocky planets are Rosetta stones in classifying and understanding the multiplicity of planetary systems that exist in our galaxy. In time, statistics on the formation and evolution of exoplanets will be available and will provide vital information for solving some of the unanswered questions about the formation, as well as evolution of our own world and solar system. Special attention is paid to the biosignatures (signs of life) detectable in the Earth's reflected spectra and the search for life in the universe. The authors are experts on the subject of extrasolar planets. They provide an introductory but also very much up-to-date text, making this book suitable for researchers and for advanced students in astronomy and astrophysics.