Molecular logic-based computation is a relatively young field but mature enough for its story to be told. It is a growing branch of chemical science which highlights the connection between information technology (engineering and biological) and chemistry. With his co-workers, the author launched molecular logic as an experimental field by publishing the first research in the primary literature in 1993 and is uniquely placed to recount how the field has grown. There is no other book at present on molecular logic and computation. It shows how designed molecules can play the role of information processors in a wide variety of situations, once we are educated by those information processors already available in the semiconductor electronics business and in the natural world. Following a short history of the field, is a set of primers on logic, computing and photochemical principles which are an essential basis in this field. The book covers all of the Boolean logic gates driven by a single input and all of those with double inputs. The wide range of designs which lie beneath these gates is a particular highlight. The easily-available diversity of chemical systems is another highlight, especially when it leads to reconfigurable logic gates. Further on in the book, molecular arithmetic and other more complex logic operations, including those with a memory and those which stray beyond binary are covered. Then follows molecular logic with quantum aspects and finally, the book catalogues the useful real-life applications of molecular logic and computation which are already available. This book is an authoritative, comprehensive, state of the art, reference and a 'one-stop-shop' for scientists, academics and postgraduate students in this field.