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for sharing information has brought with it the corresponding ubiquity of URL references and citations. URLs regularly appear on billboards, packages, business cards, print advertisements, clothing, and as references in scientific articles. Most readers have probably experienced a “dead link”: a Web reference that for a variety of reasons will not lead to a valid or correct Web page. A dead link stemming from a URL appearing in the context of everyday life is usually a minor inconvenience that can be resolved by using a Web index or a search engine; it will seriously affect only the future archeologists trying to untangle the web of our daily lives. On the other hand, a dead Web link appearing in a scientific article has wider implications. Citations in scholarly work are used to build upon existing work, substantiate claims, provide the context in which research is performed, and present, analyze, and compare different approaches or methodologies. Therefore, references that cannot be located seriously undermine the foundations of modern scientific discourse. The objective of this article is to examine, quantify, and characterize the quantity and quality of Web links used in computing literature. Our aim is to provide definitive information related to the availability of URL references as a function of their age, their domain, the depth of the path used, as well as the technical reasons leading to failed links. Our research has been greatly aided by the emergence of online versions of traditional paper-based publications [4]. By tapping into the online libraries of the ACM and the IEEE Computer Society we were able to download, extract, and verify 4,375 Web links appearing in print articles during the period from 1995–1999. Here, we describe the technologies related to Web references and retrieval, outlining the methodology we followed, presenting the results obtained, and discussing their implications. Internet resources are typically specified using the string representation of Uni-