From the first attempts to split the atom to the discovery of the top quark, the 20th century has witnessed a revolution in basic physics. Probing successively smaller constituents of matter has also revealed the conditions present at the time of the Big Bang. In a series of essays by scientists who have been closely involved in this exciting research, 'The Particle Century' describes the unprecedented advances in our understanding of the Universe. Just over a hundred years ago, the discovery of the electron showed that atoms were not the bedrock of the Universe. This modest experiment heralded a new conception of the small-scale structure of matter in terms of subatomic particles. Unravelling the details of this minuscule world, using machines and equipment of unparalleled complexity, has taxed the ingenuity and imagination of the world's most gifted scientists, and has totally transformed our picture of the entire Universe. The implications of this new understanding of the ultra-small now extend to the largest scales of space and time, suggesting how the Universe itself could have evolved from a chance quantum fluctuation. Thanks to particle physics the answer to the oldest question of all - how was the Universe created? - is within our grasp. Covering the major developments made during this, the Particle Century, including early accelerator physics, the rise of the Standard Model and the new comprehension in terms of the Big Bang, and extending right to the cutting edge of today's investigations, these essays add new insight to the continuing efforts to unravel the deepest secrets of Nature.