This chapter discusses the conventional term 'reader' with the understanding that the act of reading an app includes viewing, listening, and, in many cases, playing. As a field of academic research, that of digital picturebooks is nascent but rapidly expanding. Several studies draw parallels between printed and digital picturebooks, identifying the latter's characteristic features. While picturebook studies emphasize the materiality of the printed book, ascribing aesthetic qualities to its physical features such as size, format, paratexts, and doublespread layout, an app makes materiality ambiguous. 'Digital picturebook' seems to be the most encompassing phrase that refers to a wide range of texts delivered electronically, from e-picturebooks to texts with a high level of animation and interaction. While digital, or electronic books, including enhanced and interactive books, have been in circulation for a while, the first digital picturebooks appeared in 2010 when the first iPad was launched in the United States.