Over the last two decades alone, new technology and space missions have profoundly changed our understanding of prospective extraterrestrial life in the universe. The resulting field of astrobiology has become a highly eclectic and interdisciplinary pursuit, encompassing many of the natural sciences and holding ramifications for nearly all other areas of study. Co-written by an astrophysicist and a biologist, this introductory undergraduate textbook presents an overview of astrobiology for students from all backgrounds. Addressed in its chapters are the recent detection of potentially habitable planets and the prospects for detecting biosignatures and life; the celestial and geological factors that enabled the appearance and evolution of life on Earth; and other factors that continue to affect life up to the present, such as climate change. Based on over twenty years of university coursework, and in particular the authors' own interdisciplinary astrobiology curriculum, the text is accessible not just for the budding science major, but for any undergraduate student or lay reader excited by the prospect of life in the universe.