The Science Citation Index: A Transformative Information Resource Turns 50

In an age when all the world's knowledge seems to be at one's fingertips, it might be difficult to envision a bygone era when retrieving information meant a slow, laborious, manual slog through printed materials. For scientists and scholars in the 1950s, the task was especially arduous, relying primarily upon old-fashioned indexes to the scientific literature and their rigidly defined "subject" fields that might or might not conform to a researcher's specific intellectual pursuit. The process of finding research necessary to advance one's own work was time-consuming and hit-or-miss.

That began to change in 1955, when Dr. Eugene Garfield, a chemist turned information scientist, initially proposed the idea of "citation indexing." This was a new means of discerning relevance, connectedness, and continuity in scholarly publications, even those that were seemingly disparate. In 1964 Garfield put his idea into practice with the Science Citation Index (SCI), produced at the company he founded, the Institute for Scientific Information in Philadelphia.

This year the SCI turns 50. Now known as Thomson Reuters Web of Science -- after five decades of refinement, enlargement, and the advancements of the digital revolution -- the SCI continues to provide researchers with a personal road map through the vast landscape of science.

Garfield's innovation was to jettison, in effect, the subjective attempts of indexers to organize the literature into distinct, predefined areas. Comparatively citation indexing relies on researchers themselves -- the people actually writing the publications. By engaging in the compulsory scholarly practice of footnoting previous work (thereby establishing "citations" to that work), authors convey their own judgments about the research they deem particularly noteworthy, useful, and germane to their work.

In turn, and over time, those citations constitute an intellectual trail, charting the progression and evolution of an idea or advancement. Researchers and scholars can follow this trail, identifying the previous work that inspired any given publication, and seeing how that publication was itself subsequently cited. The citations point to further relevant work, not to mention fortuitous offshoots, offering researchers a wealth of data pertinent to their own endeavors.

For those monitoring the larger progression of knowledge, citation networks also form themselves into clusters of closely related work, marking and mapping new and emergent fields of research. As a further benefit, the tracking and tabulation of citations -- to individuals, institutions, journals, and even nations -- affords an objective data point for assessing the broader impact of research, as viewed by researchers themselves.

From its earliest release as a five-volume book set to its present online incarnation as the Web of Science, the SCI is now used by nearly 7,000 institutions worldwide. It continues to guide researchers to the information they need and to serve as a constantly evolving atlas of scientific inquiry and progress.

Learn more about Dr. Garfield, the history of citation indexing, and the SCI/Web of Science and its ongoing legacy.