Social tagging is a system of content representation which is collaboratively developed by information users and made available to other users via Web 2.0 applications. In this chapter, social labelling is defined, the elements which comprise it are outlined and the criteria necessary for it to be used are discussed. Also discussed below are in-depth descriptions of the characteristics and types of social indexing of information and in addition to such critical perspectives as its usefulness as well as its strengths and weaknesses. The contribution of social indexing and social content administrators to reading for academic purposes is analysed from an academic perspective, while their impact on reading for pleasure is analysed by an examination of social reading applications.As can be seen from the above references, there is criticism as well as appreciation of social tagging. As only their usefulness can prove their worth, Goh (2009) and his co-authors investigated if documents could be assigned to their associated tags. For this purpose, the authors downloaded web pages and their associated tags from del.icio.us. Content analysis was also adopted as a part of the methodology to find characteristics of effective and ineffective tags. Based on these methodologies, the author carried out two text categorisation experiments using support vector machine classifiers. In the first experiment the author used the terms from the documents as features and in the second he included both, i.e. the terms from the documents and tags. The performance of both of these sets was tested using criteria such as precision, recall, accuracy and F1 score. The results indicated that: (i) the tags did not have much impact on the performance on either side, i.e. did not improve or degrade much; (ii) all tags are not useful in resource discovery by public users, thereby confirming that there may be other dynamic reasons for tagging which only the tagger knows. These conclusions may be useful to library and information professionals for contributing to the social tagging system and using tags and tagging for development and management of information storage and retrieval systems. Folksonomies are useful for enhancing interactivity of public library catalogues; they also help users to organise personal information spaces, supplement existing controlled vocabularies and form informal online communities of interest (Spiteri,2006). Folksonomies are also useful for initiating user-driven readers’ advisory services (Spiteri,2007). Application of tagging by medical librarians is reported by Bianco (2009), who cites a survey of tagging by Americans, which indicated that use of tagging is not restricted by income, age or ethnic group.