The project ›Index‹ is dedicated to interactive instruments and variants in the digital book medium. Is a digital carrier medium more clearly and sensibly suitable for interactive use? How can concepts and designs animate and motivate readers to interact? Where are the many possibilities of narration besides linear from A to Z?

An app is being developed for this question, which conceives the digital book medium as a non-linear and multimedia index. In contrast to most digital media, it represents a »closed space« in which content (image, text and video) is linked without having to be read linearly.

The concept of the index is examined with regard to the meanings register, index and index finger. The representation of the index finger is the central design element of the app and at the same time functions as an example of possible content.