Gestural annotations

Gestural annotation is described, for example where sensors such as touch screens and/or cameras monitor document annotation events made by a user of a document reading and/or writing application. In various examples the document annotation events comprise gestures recognized from the sensor data by a gesture recognition component. For example, the gestures may be in-air gestures or touch screen gestures. In examples, a compressed record of the sensor data is computed using at least the recognized gestures, document state and timestamps. In some examples the compressed record of the sensor data is used to facilitate consumption of the annotation events in relation to the document by a second user. In some examples the sensor data comprises touch sensor data representing electronic ink; and in some examples the sensor data comprises audio data capturing speech of a user.