Our journey in search of the origin of matter — and, by extension, the origin of the Universe itself — has taken us deeper and deeper inside atoms. First to come into view was the atomic nucleus, and still further downscale the individual protons and neutrons that constitute the nucleus. At least for three decades, nucleons (protons and neutrons) were considered to be our final destination. Then, peering into them, we detected shadows of yet another layer of matter that lurks inside. Unable so far to crack open a nucleon and bring out one of these shadowy objects for observation and measurement, we can only guess what they are. We have named them quarks. We believe that two types of quarks — one named “up” and the other “down” — make up the proton and the neutron. Quarks are held together by a force dubbed the chromo force, represented by particles named gluons, which are just as unseen as quarks. So it is the quarks and gluons that lie at the bottom of all known matter!In this important book, the major developments in atomic, nuclear, particle and quark physics over the past one hundred years are presented in a style that is both accessible to the layperson and of value to the expert. It provides a brief history of particles, charting the discovery of electrons and photons, antimatter, atomic nuclei, strong and weak forces, and quarks and gluons. In particular, it traces the concept of “conserved charges”, a phenomenon that is consistently manifested in each of these milestone developments in modern physics.