Chapter 4: Metadata Magic 83 Related to personal content, folksonomies are of specifi c interest (Mathes 2004). A folksonomy consists of collaboratively generated, open-ended labels that categorize content, such as Web pages, online photos, and Web links. A folksonomy is a taxonomy where the authors of the labelling system are also the main users, and sometimes creators, of the content. The labels are referred to as tags and the labelling process is tagging. In general, metadata describes the document’s content, context, or structure (Kennedy and Schauder 1998). Although metadata often comes in a textual or numerical format, it should not be restricted to these, since some objects can be described far more effi ciently with other content formats. For example, a thumbnail image embedded into a JPEG image fi le is clearly metadata since it provides a summary of the actual content and acts as a surrogate when, for instance, browsing several photos. 4.1.2 Metadata – For Managing or Enjoying? Traditionally, metadata has been the business of content management professionals, such as researchers in information retrieval (IR), librari- ans, and news archivists, among others. From this point of view, there are several ways to categorize metadata, such as that of Gilliland- Swetland (2000): • Administrative metadata that is used for managing information resources, such as copyright; • Descriptive metadata that describes or identifi es information resources, such as vocabularies and annotations; • Preservation metadata that enables information preservation man- agement, such as physical condition of resources; • Technical metadata that illustrates how a system functions or meta- data behaves, such as formats and compression information; • Use metadata that describes level and type of information use, such as user tracking. The above list is typical of the professional content management view- point: analytic, technical, neutral, functional. However, iPod-toting youngsters are not interested in the metadata in their players, as long as it does the magic and helps them to fi nd the “good stuff”. They might choose altogether different categories for metadata, such as the following for describing music: