It is helpful to distinguish between two usages of deixis, gestural and symbolic, as well as non-deictic usages of frequently deictic words. Gestural deixis refers, broadly, to deictic expressions whose understanding requires some sort of audio-visual information. A simple example is when an object is pointed at and referred to as "this" or "that". However, the category can include other types of information than pointing, such as direction of gaze, tone of voice, and so on. Symbolic usage, by contrast, requires generally only basic spatio-temporal knowledge of the utterance. So, for example