Acknowledgements Because I know so many of the people whose work is described in this book, I have been shameless in asking them for help. Amy Friedlander, the founding editor of D-Lib Magazine, has been a constant guide. My wife Caroline introduced me to digital libraries when she was a graduate stu- dent at MIT in 1966. Now at the Library of Congress, she helped with many sections throughout the book. Individuals who have made comments on the manuscript or checked specific sections include Robert Allen, Kate Arms, Steve Cousins, Gregory Crane, Jim Davis, Peter Denning, Jack Dongarra, George Furnas, Henry Gladney, Steven Griffin, Kevin Guthrie, Larry Lannom, Ron Larsen, Michael Lesk, Ralph LeVan, Mary Levering, Wendy Lougee, Clifford Lynch, Harry S. Martin III, Eric Miller, Andreas Paepcke, Larry Page, Norman Paskin, Vicky Reich, Scott Stevens, Terrence Smith, Sam Sun, Hal Varian, Howard Wactlar, Donald Waters, Stuart Weibel, and Robert Wilensky. Earlier versions of chapter 4 were provided to the Fundação Getulio Vargas and the Ticer Summer School. A sketch of chapter 8 was presented at the SGML/XML Conference in 1997. Panel 6.3 is from the U.S. Copyright Office. The figure in panel 7.3 is based on a figure by Henry Gladney. The list of elements in panel 10.3 is from the Dublin Core web site.