Introduction

Research and development in digital libraries (DLs) have progressed significantly over the past 20 or so years. A search on the Scopus database reveals a dramatic rise in the number of publications (articles, papers, reviews), from 436 publications between 1990 and 1999 to 7469 publications between 2000 and 2010 (Nguyen and Chowdhury, 2011). A number of reviews have been written to trace the developments and major areas of DL research. For example, Chowdhury and Chowdhury (1999) reviewed and classified DL research in the 1990s in the following major areas: collection development; development methodology and design issues; user interfaces; information organization; classification and indexing; resource discovery; metadata; access and file management; user studies; information retrieval; legal issues; social issues; evaluation of digital information; evaluation of DLs; standards; preservation; and implications for library managers.

More recently, Pomerantz et al. (2006) studied a sample of 1064 DL publications covering the period 1995–2006 and suggested that DL research and work can be broadly grouped into 19 modules (core topics) around 69 related topics. Another review of DL research, conducted by Liew (2008), was based on 557 publications covering the period 1997–2007. These publications collectively centred around five themes (core topics) and 62 related subtopics. These two studies provided fundamental frameworks of DL core and subtopics, with Pomerantz et al. (2006) covering core computer science and library and information science topics and Liew (2008) covering the organizational and people issues of DL research.

The most recent DL knowledge map proposed by Nguyen and Chowdhury (2011) includes 21 core topics and 1015 subtopics. In addition to the classic research topics in information and library science such as collection management, information organization, information retrieval, user studies, human–computer interactions and digital preservation, they noted several new research topics such as ontology and semantic retrieval, virtual technologies, mobile technology, the semantic web and social networking.

As discussed in the literature (see for example, Nguyen and Chowdhury, 2011;

Pomerantz et al., 2006; Liew, 2008) and in different chapters in this book, research and development activities in DLs are significantly influenced by several factors such as ICT developments, changes in the socio-political scenario, and new business models appearing within the information industry vis-à-vis new regulations (including copyright and access management regulations).