The book chapter "Digital Identity" in the Handbook "Digitization of the State and Public Administration" analyzes digital identification and authentification technologies and their impact in public administration and society. First, it introduces and defines the concept of digital identity. Second, it gives an overview of the technologies' applications in public administration and beyond. Third, it analyzes their governance and implementation in Europe and Germany. Fourth, it presents perspectives for the future development of digital identity in increasingly networked societies.