Exotic Mesons at Electron-Positron Colliders

According to the conventional quark model, mesons are bound states of a quark and anti-quark. This model has been tremendously successful in describing the properties of a wide range of mesons, from the lightest pions (made with up and down quarks) to the heaviest Upsilons (made with bottom quarks). However, a barrage of recent experimental results suggest that more complex mesons exist, such as tetraquarks, meson molecules, or hybrid mesons. The ongoing attempt to understand these experimental results has been leading to new insights into the way the strong force works. In this talk, I will review the experimental status of a variety of candidate exotic mesons with an emphasis on results unique to electron-positron colliders.