This book provides a lively and engaging introduction to the science and technology of astrobiology and our prospects for interacting with extraterrestrial life. In just over two decades, there are now more than 3,000 known extrasolar planets, some of which may be Earth-like. From the author's long experience teaching a course on this topic, he uses the Drake equation as a theme for explaining many aspects of astrobiological study, such as estimating the number of planets with microbial life, intelligent life, and communicative life. The book also includes a final chapter with examples from modern day science fiction.