The theme of this book is life in the Universe, focusing on two questions: How did life begin on Earth? Is there life elsewhere in the Universe? In an attempt to find the answers to these questions this book explores the origin and early evolution of the Earth and explains why this is not only of interest in itself, but also guides the search for life beyond the Earth. It looks at the rest of the Solar System, to see whether any other planets or their satellites have life on them today or have supported life in the past. It looks beyond the Solar System, at the evidence for planets around other stars, and how life may be discovered, should it exist, on these extrasolar planets and briefly at the search for extraterrestrial intelligence (SETI).