Artificial life, a field that seeks to increase the role of synthesis in the study of biological phenomena, has great potential, both for unlocking the secrets of life and for raising a host of disturbing issues-scientific and technical as well as philosophical and ethical. This book brings together a series of overview articles that appeared in the first three issues of the groundbreaking journal Artificial Life, along with a new introduction by Christopher Langton, Editor-in-Chief of Artificial Life, founder of the discipline, and Director of the Artificial Life Program at the Santa Fe Institute.