Gene therapy is a field of medical science that focuses on the genetic modifications of the cells to achieve a therapeutic effect for the treatment of a disease by repairing defective genetic material. The main objective of gene therapy is to fix a genetic disorder at its source. For example, if mutation in a certain gene occurs in an inherited disease which results in the production of a dysfunctional protein, then, gene therapy can be used to incorporate a copy of this gene that is normal and does not contain the mutation, and thus, produces a functional protein. This strategy is used to treat inherited retinal diseases and is also known as gene replacement therapy. This book outlines the therapeutic management and strategies of gene therapy in detail. It traces the progress of this field and highlights some of its key concepts and applications. For someone with an interest and eye for detail, this book covers the most significant topics in the field of gene therapy.