This chapter presents current research demonstrating that orthographic variation does not only occur naturally in historical texts, but also shows systematic patterns and functional uses. Premodern orthographic systems are flexible and offer room for innovation. This is a decisive characteristic and an important precondition for orthographic variation and change. This chapter includes an overview of types and functions of historical orthographic variation and different processes of orthographic change on the basis of examples from the history of German and from runic writing. It aims, on the one hand, to give a general introduction to the topic, and, on the other hand, to discuss theoretical and methodological issues in the study of variation and change in historical orthography that provide a background against which a research question and design for the study of variation and change in historical orthographies can be defined.