Book excerpt: INTRODUCTION This is part of a series called Hubble Focus. Each book presents some of Hubble's more recent and important ob- servations within a particular topic. The subjects span from our nearby solar system out to the horizon of Hubble's ob- servable universe. This book, Hubble Focus: The Lives of Stars, highlights some of Hubble's recent discoveries about the birth, evolution, and death of stars. Hubble's contributions are often in partnership with other space telescopes as well as those on the ground, and they build on decades of discoveries that came before Hubble's launch. Its findings are helping us under- stand how our universe has come to be the way it is today.