Introduction

Services in Web 2.0 generate a large quantity of information, distributed over a range of resources (e.g. photos, URLs, videos) and integrated into different platforms (e.g. social bookmarking systems, sharing platforms (Peters, 2009). To adequately use this mass of information and to extract it from the platforms, users must be equipped with suitable tools and knowledge. After all, the best information is useless if users cannot find it: ‘The model of information consumption relies on the information being found’ (Vander Wal, 2004). In Web 2.0, the retrieval component has been established through so-called folksonomies (Vander Wal, 2005a), which are considered as several combinations of an information resource, one or more freely chosen keywords (‘tags’) and a user. Web 2.0 services that use folksonomies as an indexing and retrieval tool are defined as ‘collaborative information services’ because they allow for the collaborative creation of a public database that is accessible to all users (registered, where necessary) via the tags of the folksonomy (Ding et al., 2009; Heymann, Paepcke and Garcia-Molina, 2010).

Folksonomies in information retrieval serve mainly to provide access to information resources for all users – where the initial motivation for tagging is often of a personal nature:

Metadata in the form of tags, titles or descriptions are especially invaluable for the retrieval of non-textual information resources such as images or videos because the state of the art of search engine technology allows only for textual research, meaning that these resources would otherwise be irretrievable (Dye, 2006). In these instances, it is also important for the retrievability of resources to be guaranteed by a broad-access vocabulary, and this is where folksonomy can provide excellent service (Goodrum and Spink, 2001, 296). Because of their strong user-orientedness and broad-access vocabulary, folksonomies can also facilitate the retrieval of relevant information in company intranets or in ‘enterprise search’ (Schillerwein, 2008).