The emergence of digital libraries in the early 1990s was a turning point and a critical component of the worldwide, world-changing shift to networked information. The turning point crystallized from myriad disparate elements that had influenced and combined with one another, in the process creating something entirely new. The high energy and important outcomes of that first, formative digital library decade created further winds of change that in turn produced more vigorous activity. More than 20 years on, we can observe a young, multidisciplinary field of digital library research and practice that has now reached a new intersection of dynamic forces – one dominated by the social web. This is the context in which I wrote this book.

The intention of the book is to help advance learning, professional discourse, research and practice at this particular moment in the evolution of digital libraries. I have done my best to take a broad, international perspective. At one level, I have approached the subject generally: the foundations, current practice and prospects of digital libraries. A second structural theme runs through the book as well: digital libraries in the context of the web-based communities they serve. In particular I explore the possibilities of a shift toward a community-centered perspective based on what digital libraries contribute or might contribute in a time of large-scale, web- and networkdriven societal change.

The book attempts to place insights gleaned from the record of digital libraries’ first decade, the second decade's literature of research and practice, conversations with several digital library experts, and my own research and experiences into an overarching framework that can make sense of an enormous amount of activity. Over the course of twenty-some years, thousands of people from multiple disciplines and domains have contributed to this young field of endeavor. The book's structure, topics and analyses reflect my own perspective, interpretations and knowledge of all this work; it may be an understatement to say there are other perspectives. I have cited many sources in this book, not only to place the chapters and sections in the context of related work, but also to guide those who wish to explore specific topics in more depth or from other points of view.