The unique role of strangeness in nuclear physics has recently attracted much attention, from both the theoretical and experimental viewpoints. This is due not only to the broad spectrum of possible hadron many-body systems with strangeness, but also to the fact that strangeness gives us an opportunity to study fundamental baryon-baryon interactions in a new perspective. Our knowledge of this subject has widened as the scope of hypernuclear experiments has expanded from strangeness exchange and the associated production reactions to hypernuclear weak decays, β decays, cascade hypernuclei, double-Λ events, electroproduction of strangeness, etc. This trend will be accelerated by the full operation of new laboratories such as TJLab, COSY, DAΦNE, JHF, MAMI, and others. Various aspects of those important and exciting topics are discussed in this book in order to get a perspective of this fast developing area of nuclear physics.