The word metadata emerged in the late 1960s from the information technology sector,1 and has become ever more inescapable with the advance of digital technology. It is often defined, not particularly helpfully, as “data about data.” This means that metadata provides information about content-in the museum context probably a document or work, or group of the same-that may exist in analog or digital form. Metadata may be defined as information by means of which we hope to not only identify and describe, but also to control and continue to exploit our collections, both analog and digital (see Baca, 1998b; National Information Standards Organization, 2004b). This is a very broad definition, and indeed some would argue that the term metadata has been stretched to apply to things for which perfectly good and more precise words already exist, such as catalogue or registry. Cataloging and metadata are in fact terms used by different communities to describe identical, or at least overlapping, activities that serve the same purpose: the management of collections. Because of its expansive brief it has proved necessary to split metadata out into various categories-descriptive, administrative, technical, and so forth-depending on its origin and use. Metadata can exist in almost any form, and again need not be digital, but it is most likely to be useful to a wide number of people over a long period of time when it is structured, semanticallycontrolled, and machine-readable.