We examine a crucial question for the World Wide Web: What does a Uniform Resource Identifier (URI) mean? Crucial for the next-generation Semantic Web, can it refer to things outside web-pages? The Web is a universal information space for naming and accessing information via URIs. However, the classical philosophical problems of meaning and reference that have been the source of debate within the philosophy of language return when the Web is given as the foundation for a knowledge representation with the (...) Semantic Web. Debates on the Semantic Web about the meaning and referential status of a URI are explored as analogues to debates about the meaning and reference of names in the philosophy of language. Three main positions are inspected: the logical position, as exemplified by the descriptivist theory of reference, the direct reference position, as exemplified by Putnam and Kripke’s causal theory of reference, and a Wittgensteinian position that views URIs as a public language, as exemplified by Web search engines. These positions show that debates within the philosophy of language are alive and well on the Web, and so in the philosophy of computer science. (shrink)