The book - the author's dissertation - looks at the museum, at the devices the museum uses to support the museum user, and at the ways in which those devices operate. The museum is defined as an institution in which labels consistently confer specific properties on users. The museum can be analysed in terms of the labels it creates, and the properties created by those labels. Different labels give rise to different properties - interaction in the museum is among the properties created by museum labels. This study concerns the museum as a complex support system in which strategies adopted at the level of the label determine the character of the museum experience and its ability to support unknown and unknowable users, and argues further that it is the choice of user-language which is the key determinant of the label's effectiveness in the museum setting.