Exotic Hadrons from B Factories

The first generation of B-Factories, BaBar and Belle, operated over the previous decade and produced many world-leading measurements related to flavor physics. One of the most important discoveries was that of an apparent four-quark particle, named X(3872). It was the first of a growing X, Y, Z alphabet of exotic hadrons, now numbering more than a dozen, found by the $e+e-$ collider experiments. These multi-quark states represent an unusual departure from the standard description that hadronic matter consists of only two or three quarks. These discoveries have led to the emergence of a new category of physics within heavy meson spectroscopy. This talk will review some of these key experimental results, and highlight the potential of the next generation B-Factory, Belle II, as it begins operation in the coming year.