The technology of the coming decades may enable us to explore the nearest stars outside our solar system with robotic probes and perhaps even observe some of the recently discovered planets orbiting these stars. This book examines the reasons for exploring our stellar neighbors and the technologies we are developing to build space probes capable of overcoming the vast distances between stars. To reach the nearest stars, we must first develop a propulsion technology that can get our robotic probes there in a reasonable time frame. Such propulsion technology has radically different requirements compared to conventional chemical rockets, due to the enormous distances that need to be covered. Surprisingly, many propulsion concepts for interstellar travel have been proposed and are just waiting for practical engineering solutions and the political will to bring them to fruition.