Associative rings that possess Morita dualities or self-dualities form the object of this book. They are assumed tohave an identity and modules are assumed unitary. The booksets out to give an extensive introduction to thisclassof rings, covering artinian rings, ring extensions, Azuma-ya's exact rings, and more. Among the interesting resultspresented are a characterization of duality via linear com-pactness, ring extensions with dualities, and exact rings.Some basic knowledge of rings and modules is expected of thereader.