What is the electron?, brings together papers by a number of authors. The main purpose of the book is to present original papers containing new ideas about the electron. What is the electron? presents different points of view on the electron, both within the framework of quantum theory and from competing approaches. Original modern models and hypotheses, based on new principles, are well represented. A comparison of different viewpoints (sometimes orthogonal) will aid further development of the physics of the electron. More than ten different models of the electron are presented here. More than twenty models are discussed briefly. Thus, the book gives a complete picture of contemporary theoretical thinking (traditional and new) about the physics of the electron.